The easiest way to get started with GWT is to use the gwt-maven-plugin and run the archetype:generate command. It will generate a skeleton project for your that you can use to compile and run a GWT application.
Below is the command to generate the skeleton:
mvn archetype:generate -DarchetypeGroupId=org.codehaus.mojo -DarchetypeArtifactId=gwt-maven-plugin -DarchetypeVersion=1.2 -DgroupId=myGroupId -DartifactId=myArtifactId
By default this version of the archetype uses GWT 1.7.1. Change the GWT version in the pom.xml to a 2.0.x version and you are ready to go!
Launch the generated application with the following command:
mvn clean install gwt:run