Hi, Emily56.  How you put your rollers in depends on the kind of look you want.
If you want an 80's type big hair look:
Starting at the top of your head take sections of hair and roll back towards the crown.  Be sure to hold the hair and roller straight up, then roll down to the scalp without pulling the hair.
If you have bangs, roll them forward.
Then, starting on one side of your head in the back, take a section and roll it in toward the center.  At this point, I alternate rolling one on the left side and then one on the right, then move on to the next one down.
From here, take a section infront of the one at the top in the back of your head and roll in toward the center.  Continue on this side of your head-ending at the front, and then repeat with the other side.  You are always rolling the sides toward the back center part.

I am left handed, but ambidexterus so I hope I'm not confusing you!

If you want a nice curly look, roll under.  I pretty much use the same "layout" of placement no matter how I actually roll the curlers.

If this is unclear, please let me know.

Good Luck!