HELP!!! I NEED TO FIX MY PC!!?

[Cyborg]

Whenever I get on the web there are loads of bs ads on sites that don't have ads at all, like Facebook and such, that weren't there before. how do i make them go away? i don't have money to spend on my pc so whatever i can find to fix it has to be free. thanks to anyone who can help! ^_^
the URL box says that the pages are encrypted, i am not sure what that means but i know its not good...

[Menace]

Download MalwareBytes from http://www.malwarebytes.org/ . Install it, run it and do updates, run a full scan and follow the prompts to clean out the malware you have.