Grab yourself aa ding kit from a surf shop and patch it up. Even a tube of Solarez (or similar) should do the job easily if it's a small ding as you describe.
Need a pic to know what your taliking about, if in doubt as Ben said get some solarez, just make sure you get the right one if your board is Epoxy because PU solarez will melt EPS foam.
if there is a surf shop that fixes dings or even a local shaper that sells surf gear go to them and take your board with you. If they are any good they will sell you the right gear for the job and give you some advice on how to fix it.
I regularly go on surfing holidays and as I recently turned 16 I have just got my first "proper" board!! However I think it may have a small ding right near the nose of the board but I am unsure if it is and if it's a problem or not,, it is about half the size of my little finger nail and is a tiny circle. If someone could give me some advice that would be great thanks :)