Custom Ranks

I have been here for four months today,and I was wondering how you use a custom rank.
I've tried editing my profile and options. I can't think of any other ways. (Remember:I'm stupid) If someone could help me out,it would be appreciated.

Next time before you create a new thread reguarding custom ranks, check to see if there was one made recently.
Yet another Custom Title Thread

This thread here was just closed not a day or so ago. Read it and all your answers shall be answered.