How to not get in trouble
What is copyright?
The official definition of copyright is the exclusive legal right, given to an originator or an assignee to print, publish, perform, film, or record literary, artistic, or musical material, and to authorize others to do the same. In other words, if someone has something that they created and it is copyrighted, you can not copy it or take it without siting that you took it from them or it is illegal.
What is Fair use?
Fair use is a legal doctrine that permits limited use of copyrighted material without acquiring permission from the rights holders. In other words or more simple form, it permits you to use some of other peoples word without siting. These statements are limited, so don't think you can get away with anything.
What to look for
What is the Creative Commons Licence?
The creative commons licence is a public copyright license that enables the free distribution of an otherwise copyrighted work. The Creative commons is a non profit organization that is devoted to expanding the range of creative works available for others to build upon legally and to share.