Main things are roundwound, which you have on it, that is wire wrapped around more wire, so bumpy. The other sort is flat or tapewound, which are smooth and a bit special, probably not something to tinker with at this point. As far as roundwounds go there are nickel and stainless steel. Steel is generally agrressive and bitey, both in sound and on your fingers. Your best bet would be some standard nickel round wound. Theres lots of other fun things to try like nylon wounds and such, but nickel rounds are the middle simple ground, turn down your tone a bit when they are brand new as they are super zingy, but that soon goes.
Guage is the nest fun, there are a few thicknesses of strings, depends how you play, .045-.105 is standard, can go lighter or heavier, heavier means harder to push down and more tension, but thicker sound to an extend. Again, probably stick in the middle ground.
Keep your old stings, you might miss them.