First of all, make sure you have m2eclipse-wtp installed (
http://m2eclipse.sonatype.org/sites/m2e-extras)
You need to select war packaging, when setting the
maven configuration (or If your project is already created, change the packaging to war).
Eclipse WTP doesn't use the same defaults as Maven (or m2eclipse for that matter).
You should configure warSourceDirectory in the maven-war-plugin, so it points to WebContent (
http://maven.apache.org/plugins/maven-war-plugin/war-mojo.html)
In any case you will need to right-click on your project, Maven > Update Project configuration.