SCT XCAL 2 help

I just got the sct xcal2 and it didnt come with any instructions, i know that u plug it in and I did that im not that stupid I just dont know if u just plug it in and go or what, I went to CUSTOM TUNE and all of that i dont know what to do or what any of that means, if i am suposed to change all that, leaner richer all that because i plugged it in and couldnt really tell that much of a differance sorry for the long post and if yal have to answer long but i really would like to know about all of it:dunce: thanks alot