the marks on the metronome refer to the number of clicks per minute. ie 60 is 1 click per second, 120 is 2 clicks per second.
you will encounter varying accounts on how to use your metronome. some people argue that you should only turn it on for a few seconds to get a feel for the pulse, then turn it off to actually play. others argue that you should be able to play the piece with the metronome clicking away, and that you should start very slowly and ratchet up to your eventual tempo. you will see different accounts for how many clicks per beat, and it will clearly vary for the situation. for instance, if you're working out tough syncopations, it's handy to make it click very slowly (ie 40), for each 16th note, or whatever the smallest division is, and then speed it up once you get the alignment/coordination down.
hopefully that makes some sense. the wording of your question was a bit confusing; I hope I have answered it.