well, here is the thing, its not gonna work on your phone lol
adb commands are generally things you run with android debugging on and the phone plugged into the computer through the command prompt using the adb.exe and its two dll files
if you want to copy it to sd card and just copy it somewhere from there though you can run this in the terminal on the phone
dd if=/system/whatever.apk of=/sdcard/whatever.apk
might have to run su before hand to be able to read it properly though
and obviously youll be changing whatever.apk to the actual name of the file
if you want to do adb through a computer though we can walk you through that too
generally i like to toss adb.exe and its two dll files it comes with into windows\system32 that way its always found no matter what, then open up a command prompt and run it, if you were able to run the root method you should already have the drivers so thats out of the way, but basically there is little you can do with the thing directly on the phone so if youre trying to modify the ui without the use of a pc i wish you the best of luck...