How long to heat pizza for in the oven?

I ordered out a large cheese & peperoni pizza last night and had a few slices left over and I put them in the fridge in plastic wrap. Well, I want to eat 2 slices now. What do I preheat the oven to? And how long do I keep them in the oven for. Geez, my parents are asleep and I really am not a cook lol. Please help!