help i have a trojan horse on my laptop

i have a trojan horse on my laptop.. my son played on a game site and im assuming thats where its from.. im not computer literate so i have no idea wat to do.. the file is iwingameshookIE.dll .. i have tried to remove it but it wont let me.. ive tried to quarantine it but it wont let me.. and now im stuck.. i have absolutely no idea wat to do next please help... anyone????