i agree, this is the right process. Tramain helped me get my 3GS jailbroken and i'm glad i did. but i come from a background of BB hacking and lots of computer experience. so like iMuggle said, if you're not comfortable, don't do it.
however, if you still want to do it...download both linked files that Tramain sent you. save them (don't open them) to your desktop so they're easy to find. then once they are downloaded, unzip redsn0w. inside the unzipped folder, you'll find a file called "redsn0w". open this file and it will start the process of JB. then once it asks you to locate the IPSW file, click "Browse". now find your IPSW file you downloaded from Tramain (hopefully on your desktop). after your PC verifies this file, you can start the JB process. i started with my phone both on and connected to the USB. follow all instructions on your PC from here forward. after it's finished, you'll be free!