Download ios I wanna download and installing this app

You can try different ways to update iOS. One of them shows below.

If a message says that an update is available, you could then click "Install Now" button to start to update your iPhone iOS software. Also, you could manually check whether there is an iPhone iOS update or not on your iPhone. The below steps would show you how to update iPhone software wirelessly:

1. Before you update iPhone software via WiFi connection, you need to make sure your iPhone has enough storage and battery to support the iPhone update.
2. Connect your iPhone to a WiFi network.
3. Tap "Settings > General > Software Update" successively.
4. Tap "Download and Install" option when your iPhone has detects an update available. If a message asks to temporarily remove apps because iOS needs more space for the update, tap Continue or Cancel. Later, iOS will reinstall apps that it removed.
5. Then iPhone would start to download and install iOS update immediately. You only need to wait for the update complete.

For more methods, check: How to Update iPhone

Either the Operating System (IOS) on the tablet or the tablet hardware itself is too old to run the app(s). Check for and install an IOS update and try again. If the hardware (tablet) is too old, you'll have to replace it to install the app(s).

Yes!
Most people are now on iOS 8.4
So.... do you mean back grade? from 8 to 7
iOS 9 will be released in a few days!
https://www.apple.com/ios/

It can be downloaded & installed directly to your iPhone/iPad
Or... as I prefer.....
use my computer running iTunes to firstly Backup the iDevice (using it's USB charge cable)
ITUNES will at this time indicate that there is an update available for your iPad.
Choose to "download only" the new iOS.
If you have other things to do!
Disconnect while the download takes it's time downloading.
Then come back later and plug in USB cable and "Install" the updated iOS.
How to Update iOS Software on an iPad

Facebook on old iPads with iOS 5.1.1:
It is possible, a bit tricky, but possible. First, you'll need to download the Facebook app through iTunes on your computer, this will make it show up as "purchased" in your library.
After that, open up the App Store on your iPhone and go to the 'purchased' tab. When you try to install it this way it will tell you that you need iOS 6 or higher, but will also ask if you would like to download an older version of the app. then click on download.
- again step by step:
1) Open up iTunes on your computer
2) Go to Store (left hand column) ->iTunes Store
3) Search for Facebook; - download the app
4) then open App Store on your iPhone
5) Click on 'Purchased'
- you will have to install Facebook by clicking on it as usual.
App Store will ask you: "Download an older version of this app. The current version requires iOS 6.0 or later, but you can download the last compatible version.",
- then click on Download and it should finally work.

Unfortunately you can only update to 5.1.1 for the ipad1

install netflix on ipad first gen.:
first make sure your iPad 1st. gen is on iOS 5.1.1 !
It is possible, a bit tricky, but possible. First, you'll need to download the Netflix app through iTunes on your computer, this will make it show up as "purchased" in your library. After that, open up the App Store on your iPad 1 and go to the 'purchased' tab. When you try to install it this way it will tell you that you need iOS 6 or higher, but will also ask if you would like to download an older version of the app. then click on download.
- again step by step:
1) Open up iTunes on your computer
2) Go to Store (left hand column) ->iTunes Store
3) Search for Netflix; - download the app
4) then open App Store on your iPad
5) Click on 'Purchased'
- you will have to install NetFlix by clicking on it as usual.
App Store will ask you: "Download an older version of this app. The current version requires iOS 6.0 or later, but you can download the last compatible version.",
then click on Download and it should finally work.

Open Safari & go to this URL.
https://itunes.apple.com/sg/app/showbox/id793056594?mt=8

bobwin

For the iPad first generation (A1219) before iOS 5 to update is only possible with connecting the device to iTunes on a computer. Plug it into your computer and open up itunes under devices click on your ipad and then click on check for update.
- but this model supports only iOS 5
- NO iOS 6/7/8 !

on a 1.gen. iPad it is impossible to install iOS6:
this model supports only iOS 5 !
- NO iOS 6/7/8
- the processor is too slow....
For the iPad first generation (A1219) before iOS 5 to update is only possible with connecting the device to iTunes on a computer. Plug it into your computer and open up itunes under devices click on your ipad and then click on check for update.
- but this model supports only iOS 5
- NO iOS 6/7/8 !

Have you installed a Baidu app on your iPad and wanna remove it?

Well, the first method recommended for you is to directly delete apps from Home screen on your iPad.
1. You only need to keep touching the icon of the app until it wiggles with an X at the upper left corner.
2. Then tap the X and choose "Delete" in the pop-up dialog. You will get the apps deleted with no efforts.

Sometimes you cannot see the X and don't know how to delete apps on iPad directly, you can check the Settings at this moment. Then you can try to delete the apps on your iPad again.
1. Check the "Settings", then scroll down a bit and tap on the "General" option.
2. Tap on "Usage" (older version of iOS) or tap on the "Storage & iCloud Usage" (newer version of iOS).
3. You need to tap on "Manage Storage" and you'll see a list of all app installed on your iPad. Simply select the app and tap on "Delete" to delete that app.

There are also some other methods to help you remove unwanted apps from your iOS device. Click the following link to know more.
How to Delete Apps from iPad