Where are you learning how to use ADB? Also, mm how did you get tmobile to send you a new phone.. lol.. I downloaded a rom with rom manager and it never finished downloading and all of asdudden i look at my phone and it will not get off of the LG splash screen. I dont know what to do. Any help and advice would be great! Thanks!!
since no one replied, rom manager only works with clockwork mod recoveries, it says it in rom manager you should have been reading it instead of just plugging away at random buttons. this brings up two points
IF you are using a cwm recovery then this is not the right thread to be asking for help.
IF you are not using a cwm recovery, this is still not the right place to be asking for help, HOWEVER, i would try shutting the phone completely off, pull battery if needed. press and hold what every your buttons are to boot into recovery mode and wipe data/factory reset. You'll have to root again, and this time read everything before you do anything.
ADB: Google the android sdk, download and install it on your computer, i HIGHLY recommend changing the install directory to c:/Android/, you'll need also need the JAVA SDK, and you can get that from java.com or by googleing 'java sdk'. Both are free and open source.
before starting on getting a custom recovery you need to check out how to root your T, im using an S so i cant help you with this, or which buttons are needed to access recovery. I've heard the z4root works for the T if it does great, you can find that by googleing 'z4root xdz' and it should be the very first result, the link should take you to the developer's post on the xda forums where you can download z4root and if you so decide to donate to them you'll be able to from there. There is an ADB rooting guide
here which i recommend as it will give you some time in adb and you can start to learn how to use it.
AFTER your rooted you can install the recovery found on this thread.