Having a high cholesterol level one day doesn't mean you're going to have a heart attack the next day ( but you might), also your levels can go up and down depending on diet etc- HOWEVER having a permanently high level isn't good and as has been said it can lead on to other complications including heart attack etc.
The good news is that getting your cholesterol level down IS something you can address quite easily by means of reasonably simple changes to your diet etc and maybe a little excercise etc. So, in a way it's good that you're able to see your high number now as that should be telling you to do somehting about it and that you can (and should) address that before it DOES becomes a bigger medical issue.
And as Gerefan2 has said - just go see your Doctor as taking medical advice from anyone on the internet is never a good idea - but for stuff like high cholesterol, well, that advice is fairly simple and straightforward and equates to the likes of "hey I'm bleeding should I try to stop the bleeding" etc - so, yes go see someone and maybe try to get your numbers down as simply put it can't do you any harm.