请这里的高手朋友帮帮忙，我中毒了

the alert says;

your computer is being attacked by an internet virus,it could be a passork-stealing attacke, a trojian -dripper or similar

attack from : XXXXXXXXX. Port XXXX

I could not get on internet from my log on, And a porn site pops up everytime I try internet





How should I fix it?

Thanks very much!
_:'(