Hey there buddy! That's actually not a stupid question at all. That's the greatest question you could ever ask. It's going to be a little difficult to explain if you're not very familiar with rhythmic notation and rhythm counts. If you are not familiar with what things are like a quarter note, 8th note and 16th note or even a rest, I suggest you look into those first.
The greatest way to practice with a metronome Truly depends, in my humble opinion, how far you are in your playing and what kind of a guitarist you want to be. How long have you been playing?