StraightTalk Data and MMS problem on iphone3gs?

Okay so today i got the straighttalk unlimited plan with my sim card and i installed it fine into my iphone 3gs but i don't want to jailbreak it because i already upgraded to ios 6 and i have tried to change my apn settings but its been very difficult and i finally got it to work but it said "E" instead of 3g and i tweaked it a bit and now it says "3G" but whenever i turn my Wi-Fi off the internet won't connect. MMS messages won't send either. I would consider jailbreaking it if it didn't harm the ios 6 or my phone. Please ANSWER! EITHER TO Help WITH MY APN SETTINGS OR WITH THE JAILBREAK Thanks

Added (1). I tried to find cellular network settings but with the new updates we don't have that anymore! My "3G" shows but its not blue like its supposed to be

Goto unlockit.co.nz from safari on the iphone make a profile, choose att.mvno

should look like this

- Select Settings.
- Select General.
- Select Network or Cellular
- Select Cellular Data Network.

- Under Cellular Data Option
APN: att.mvno
Username:
Password:

- Under MMS Option
APN: att.mvno
Username:
Password:
MMSC: http://mmsc.cingular.com
MMS Proxy: 66.209.11.33:80
MMS Max Message Size:
MMS UA Prof URL:

- Click Network Tab up the top to save

Here is the Straight Talk webpage with the APN settings.

http://www.straighttalksim.com/support.php

I don't know much about the bring your own phone program with Straight Talk.