My Laptop is now can’t boot and can’t install the window xp

I don’t know how to do my laptop to install xp professional, when i install my computer , can’t boot , say your computer have some virous and cannot found the hardrive , but i chack already in Bios ,i founded .computer say f3 press and than quick ….. so i do it the new hardisk USB external Hardisk connect install , boot the cd rom but that error appear again F3 quick why this is new hardisk can you help me how to do my laptop is compaq brand