It takes a lot to screw up a beer. The CO2 produced during fermentation helps push out the O2. As long as you don't keep opening the lid you shouldn't have much of a problem.
Typically it's best to let it set in primary (plastic bucket) for five to seven days and then go into a glass carboy to secondary for a couple weeks (depending on what you're making).
Your best off just leaving your beer alone. Take gravity readings every few days after the first two weeks to check to see if fermentation is done.
It takes a lot to screw up your beer.