The wifi symbol in the computer is off - Dell Latitude E6400 Notebook

According yo the manual, it doesn't.
The "wifi" symbol means it can see the receiver.

Have you tried turning on the wifi on the laptop. You usually will see a little blue light or a symbol on the screen like an antenna if the laptop wifi is turned on. If it is you then need to open the wifi connection screen, select the wifi network you want to use, and then type in a password if it is required. Have you tried all that.

It varies with each computer model.

Need to know your signal strength and if you're connected with proper credentials. If the wifi signal is weak, the computer may disconnect to look for a stronger signal. Sometimes ipv6 is the culprit on older computers too. Disable that and use ipv4 only. There are multiple reasons for dropped internet so the more info about your system and the conditions under which the internet is dropped will help in diagnosing the problem without sending you on a wild goose chase.

Yo! the wifi symbol on your system goes like a small tree. Please locate the symbol and press it on your keyboard. thanks

That symbol stands for CAPSLOCK and lets you know if it is on or off. when the light is on means capslock is on. when off capslock is off

I'm writing to ask you a question about MC3190G Motorola I bought. I dont know how to transfer Data to the computer via Wifi/
can you tell me. what to do? I'm looking forward to your reply ASAP.

On a laptop your wifi on off button should be on the side, it will show a little tv symbol with small arches and on the other side a little tv symbol with no arches. The one with the arches means you can get the signal and you will have to change the switch to that one. If this does not work, it is possible that you computer does not have a built in wireless adapter and you may need to purchase one. If there is a slot on the side of your computer that is PCMCIA slot, you may need to put an adapter in there. You can purchase them on ebay for as little as $10, however in the store you could be looking at $40 to $70. Cheers.

Have you tried uninstalling and reinstall the driver for the wifi adaptor?