Always sign in. If you don't have an account register for one. Even if you just want to search, sign in. There is more searchable data for those who have registered and signed in.
You can browse by location, even by parents. A parent only search sometimes brings up children you weren't aware of.
FamilySearch.org should be the first place you go to search for an ancestor.
Family Tree should be available now to the entire public, once they have signed in. If that doesn't work for you (it should) email me at email@example.com and I will get you the invite link.
Family Tree may need you to start building it yourself. If you have any difficulties, the site http://familysearchtraining.com/ is awesome for learning family tree.
The learn section is important. Video training for all levels of knowledge in genealogy research. Plus, the wiki is there. The Wiki is your number one place to research.