How to say "to found"?
創始 is usually used for small shop or brand.

創辦 may used for school or news agency. 

創立 would be normally used for a country or more formal organisation. 

Usually we won't say some brand was 創立 於 2004. That's too formal.

As for Facebook, you could say "Facebook 於2004年創立 or 成立". I think it depends on how formal the object is in your mind.