Copyright and Fairuse

I feel that you should give people their credit when you use their work. I've learned that the blog I created  is copyrighted. Anything that someone creates, being the original work is copyrighted. I also learned that Fairuse is not legal. Taking someone original work and using it as you own is plagarism. Whose to say that the author would be content with you using their work, without someone acknowledging that the fact that it's not their work if you use it. If not you will be engaged in the act of plagarism.