I do not know which password to use to connect my wireless network to my Kindle Fire

Step 1 Press the "Power" key to wake the Kindle from Sleep mode. The Password prompt displays.
Step 2 Type your best guess at the password into the Password input box. Retype password guesses a total of four times. After the fourth incorrect password entry, the Reset dialog box opens asking if you would like to reset the Kindle Fire.
Step 3 Tap "OK Reset" to reset the device to original factory settings.
Connect the Kindle Fire to a wireless network and re-register the device with your Amazon account.
Tips

• Tap the "Show" option in the Password dialog box to display the password characters as you type.
• Visit the Amazon.com Reset Password page to reset your Amazon.com password (see Resources).

Warning

• Information provided in this article applies to the 1st generation Kindle Fire. Instructions may vary slightly or significantly for other models of the Kindle Fire.

The wifi password is the password installed in the router that allows any and all wireless devices to connect to your wireless network. Unless this Kindle is the only wireless device you have, then you probably know the password, since it was used on all the other devices as well. Even if you don't know it, you may have it. If the router was from the ISP, and you didn't change anything, the wifi password may be written on the base of the router. If you DID change the password and forgot it, as long as you can access the router setup,. you can go in and create a new wifi password.

Access your wireless router and change the security settings from WPA or whatever to none and APPLY or SAVE.

Then immediately after, change the security setting back to the orginal security setting WPA or whatever.

Try it again.

If no joy, go to your Kindle and find the wireless settings and find the entry for your wireless router and delete or forget that network.

Restart your kindle and try logging into the wireless router again.

From the Home screen, press the Menu button.
Select Settings, and then select view next to Wi-Fi Settings.
In the list of detected networks, choose a network to connect to it.
If your Wi-Fi network and router support WPS (Wi-Fi Protected Setup), your Kindle will detect it.
If you don't see your network in the list, you need to add the network manually.
If the network is protected by a password or WPS (Wi-Fi Protected Setup), enter the password and then select Submit.If you don't know the Wi-Fi network password, contact the person who set up the Wi-Fi network.After you connect to a Wi-Fi network, your Kindle automatically connects to it again whenever that network is in range. If more than one network is in range, your Kindle automatically connects to the last network used.

Just a few questions.
is your computer connected to the internet with a wireless connection, or with a cable? Is the internet connection you see on the kindle, the name of your wireless router? Did you setup the wireless connection on your kindle, using your connection name (the name you gave in on the wireless router you own) and password.
If you answered one or more of these questions with a no, first solve or change that. When you don't have the answer, because you don't know, you have to asume it is a no.
please tell us you did setup the wireless connection correct, so I can look to other possibilities.

1. Swipe down from the top of the screen to show Quick Settings, and then tap Wireless.
2. Verify that Airplane Mode is Off.
3. Next to Wi-Fi, tap On.
4. Tap a network to connect to it. If you see a lock icon, a network password is required. Enter the Wi-Fi network password, and then tap Connect.Note: If you don't know the password, check with the person who set up the network. This password is not your Amazon account password.
   

After you connect to a Wi-Fi network, your Kindle Fire automatically connects to the network again when it's in range. If more than one network is in range, your Kindle Fire automatically connects to the last network used.

[Source]

1. Swipe down from the top of the screen to show Quick Settings, and then tap Wireless.
2. Verify that Airplane Mode is Off.
3. Next to Wi-Fi, tap On.
4. Tap a network to connect to it. If you see a lock icon, a network password is required. Enter the Wi-Fi network password, and then tap Connect.Note: If you don't know the password, check with the person who set up the network. This password is not your Amazon account password.
   

After you connect to a Wi-Fi network, your Kindle Fire automatically connects to the network again when it's in range. If more than one network is in range, your Kindle Fire automatically connects to the last network used.


[Source]