i have an iphone 3g version 3.1.2 (7D11) on firmware 05.11.07
I want to jailbreak and unlock to use on tmobile there are many tutorials on how but none have worked with redsnow i cant find 9 beta 3 redsnow anywhere,,
How can i go about doing this do i have to upgrade the OS i dont want to lose the firmware beacuse i want to unlock it,, any help please

To jailbreak an iPhone 3G running iOS 3.1.2, you will need to use redsn0w 0.9.3 as you indicated. You can download it in a couple of places across the internet. I can't find an official link to it anymore, all of the links on the dev-team's site are dead. Make sure to retrieve the MD5 hash provided by the dev-team and check your download against it to ensure it hasn't been modified in any way.

Doing a quick google search, I found 4 different links and all 4 of them matched the MD5 provided by the dev-team on their post about 0.9.3. One of the sites seems to have a full history of redsn0w versions, linking directly to the google code site where they are originally published:

iPhone Downloads

Grab 0.9.3 from here and use it, it should get you jailbroken.

hey thanks man it worked and the link helped me with my 3gs aswell,, one las question on my 3g 3.2.1 the cydia takes forever and wheb i use search nothing comes up. why is that?

Good question -- it could be a completely outdated server list -- the version of Cydia provided in 3.x is probably very out of date. You may want to investigate getting the latest Cydia in .dpkg form or .deb form (I can't remember which format Cydia prefers for autoinstall packages, I'm sorry!) and see how to put it in and have it auto-update. I know some of the main repositories changed and a few of the containing packages for them changed as well.