What is the best internet filter out there to download?

I want to install a thing on my computer that will keep anything nasty and vulgar from popping up or coming onto my computer and with ease (and am not computer literate, at least not when it comes to this) set it up to what I would prefer it blocking. You know, basically I don’t want any kind of lewd pics or sites and if you search something online, sometimes you get not so good sites in the search results if you aren’t careful. I want to be able to surf the net without worrying about this crap.

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