There are three different situations that you'll see when you hit the flop in any online poker game with community cards.
Situation One: Your Hand Makes Nothing
Even if you've got a playable pair like QsJs, a board that reads something like Ah8d7d does nothing at all for you. You should check/fold and wait for the next hand or bluff, if you're in late position and feel like you can steal the blinds.
Situation Two: You Have A Strong Hand
This is, of course, the preferred situation. You're...