Does my Air have malware if windows pop up when I click on any link?
You can check for malware and also make sure that you don't have some known adware installed:


https://support.apple.com/kb/HT203987


The second link is quite long, so feel free to point out one line or a paragraph that don't make sense if you need a hand digesting it and then implementing the fixes.

I've also checked into http://www.thesafemac.com/arg/ and their product free but donation supported product Adware Medic and the program and site are valuable and honest tools for fighting malware and adware. I've chipped in some cash to help them continue to make information clear and available.