As a basic start i would suggest to take a look at 5 Minutes Guide on the Maven site. If you have an existing project you should take a look in particular the folder structure and check if your's fit with the default folder structure if not change it accordingly. Is your software organized in Modules as Maven expect it? What kind of Project do you have (EAR, WAR, ?). If start you have to write a pom and define the depenencies etc. and try to compile your project via Maven...
