I was looking for some gears that could go inside the robot and move things up and down with them. Help?
I believe what you are looking for is a rack and pinion gear, the rack (a straight section of groved rail) sits inside the linear slide , and has a cart that moves up and down the linear slide, the cart contains a pinion gear, which would be the vex 12 tooth gear, and then a motor, so the gear spins and the whole cart moves up and down the linear slide.
the other option I can think of is using worm gears like a lead screw, not totally sure how this works but I know it can be done, team 62 used something like this on their robot to angle the shooter, you can watch their video on youtube to see this in action
Colin described what you are probably looking for, a rack and pinion:
http://www.vexrobotics.com/wiki/images/c/c6/RackAndPinion.JPG
But it’s also possible to get motions that are sometimes close enough to linear by using gears with large diameters. Using large gears and sliders, you could make something that functions like this, for example:
http://507movements.com/mm_392.html
You could also better describe exactly what you’re trying to do, then perhaps we could point you to more specific components. 
You could also use a winch, but those are IMO harder to implement and less effective, esepcially since the axles tend to bend.
Im not quite sure what your asking but I know that worm gears can be used for moving structures up and down.