Assuming those holes are indeed intended for V brakes, you need to get a set of brake posts. A good bike shop will likely have them, but expect to pay more than you would want to for them. I think I paid $5 for one once!
Then just install them in the frame. If you're not familiar with doing this sort of thing, you may want to have the shop do it as they're kind of important to your bike's ability to stop reliably.