First, don't place a pom.xml file in the maven bin directory. Instead create a project directory somewhere (not within maven_home)
Second, a pom.xml file is supposed to describe an artifact to be built, such as a JAR or WAR. For that you need source files (of course) and the pom.xml must at minimum contain the artifacts coordinates (groupId, artfiactId, version). That is what it is complaining about.
Third, you don't have to download the repository. Well at least not the whole thing. As you build project, Maven will automatically download the artifacts that it needs and place them into your local repository.
I recommend starting off with the basic tutorials provided in the Maven docs. After that, get both the
Better Builds with Maven PDF and
Maven the Complete Reference PDF. Once you work your way through those you'll have a better understanding. If you have questions, feel free to ask - we're here to help.