If you don't use any Anti-virus program, then yes there will easily come issues and pop-ups.
Get a Anti-virus program. From what I learned in IT class in my boarding school, I highly suggest you go and install the latest version of CCleaner. I know I sound like an annoying advertiser in this sentence but; Please trust me, I have been using CCleaner myself for years now, and it has never created any issues nor being useless. It destroys malware and blocks spyware and all that virus stuff. It will also block the 'gross sites' you're mentioning.
Go on google search and type in "CCleaner", then just click the first that leads to the CCleaner's homepage, you'll get to the correct download. I can assure you it's a free downloadable program, and I think it will take you no more than 5 minutes to get it.
I hope this works for you! If it removes the ads, you'll be able to sign into FH without interruption, and you can click as much as you wish<3