That's not a stupid question at all! I can completely relate - I just got a teacup yorkie and am struggling with the housetraining as well. From what I've heard and read, you should be watching for the "signs" your puppy gives you to tell you she's gotta go potty. Once you know what to look for it can be easier to know. At this point, while she's still relatively young, taking her out every couple hours is probably a great idea. As she gets older you can probably ease up a little bit.
Another training method I've heard of is to put a bell on the door that you take her out of, and ring it each time you take her out. She will then associate the bell with potty time, and eventually ring the bell on her own to let you know it's time.
Good luck!!