Is there anything I can do to help make my butt bigger, rounder, firmer, and a little more lifted?

Thanks!

Deadlifts, deep lunges, stairs and squats.

Deadlifts?
Sorry...don't mean to be stupid. haha

You might try a search online for pictures and a full description. Form is very important so you don't hurt your back, so make sure you're doing them right. But they're excellent for the glutes. Those and lunges really target the rear.

for the past 3 months ive been taking the stairs everywhere i go no matter how many flights it is. and ive been doing two steps at a time instead of one. ive noticed a difference in my butt, not much, but something. so i can only imagine if i did other workouts too - my butt would be amazing haha

i will be looking for pictures also.

Um, walking up lots of stairs will increase your endurance more than muscular size (hypertrophy) :)
The best butt/glute exercise is squatting. Also, as Naxis said, lunges and deadlifts.
Make sure all these exercises are weighted and do 3-4 sets of 8-12 reps.
Also, if youre squatting/deadlifting, make sure youre not doing them each more than once a week as its an extremely demanding exercise that requires lots of recovery/reset.