To import sample contributions into Eclipse you first need to import the Tuscany runtime. You then need to import the sample contribution into Eclipse as a project. Instructions for doing both of these things can be found here
http://tuscany.apache.org/import-existing-tuscany-sca-projects-into-eclipse.html
Note. these instructions refer to our 1.x code base but it holds true for our 2.x code base.
Once you have a contribution imported into Eclipse and cleanly compiling against the Tuscany runtime jars you probably want to be able to run and debug it. The easiest way to do this is with a simple Java launcher. If you import the running-tuscany/embedded-jse project into Eclipse you'll see a simple launcher program which you can copy and adjust to launch the contribution(s) of your choice.