I used a tool called a level to make sure the posts were straight
I learned about setting and leveling posts last weekend and how to mix concrete for fence footings. Here is how it goes: It involves about three people. First you put concrete packets into the cement mixer, and spray water into every once in a while. After you put it into a wheel barrow you bring it over to a hole with a post in it. One person holds the post, one person smoothes the concrete and one person shovels it around the post. Once you get to the halfway mark, you use the leveling tool, and make sure its perfectly inline. Once you fill the hole to the top, you sit and let it dry.