It depends. Some people really love making those totally enclosed bottle gardens to see how long they can keep them alive for. If that's what you're after, then don't put any holes in the lid. If it were me, I'd start with one little hole. This will allow some heat to escape when the sun hits the terrarium, and avoid cooking your plants. But it will keep the humidity in, so the plants will still like it.

I know its kinda different, but Ive had an aquarium plant in an old glass preserves jar, the kind with the clamp down glass lid, I filled the jar with water from my aquarium, added some gravel, and closed it, its been in there for about three and a half years now, I never opened it, I just leave it on the computer desk where it gets regular old house light, it has filled the jar and Im thinking on transfering it to a bigger jar but am afraid of killing it in the process, the only difference I see in the plant is that its leaves are much smaller but a lot more of them, so yeah...OK =)

No reason why you should kill it just transferring. I have a couple of plants (with only their roots in water, mind you) in an aquarium, keeping my fish company, and I routinely lift them out to clean up (as do people with plants completely submerged) and put them back with no problem at all. In fact, when you take it out, rinse (dunk) the whole thing in clean tepid water, it will thank you for it.