Logic Pro 9 making a beat with a loop?

Hi, I've been trying to take the loop called "Hip Hop Power long" and make parts of it last a lot longer, while it still keeps the same tempo. I'm finding it extra hard to cut a part of it, and then paste it on while keeping a consistent tempo without missing or doubling beats etc.

What is the best way to do this with any beat loop?

I can't just click look either because it will go back to the beginning of it, and i don't want to start at the beginning, i want to continue parts in the middle and then paste them again, but i'm having trouble making beats longer than they are while keeping the tempo even and everything else. etc