Create your release package by creating a publish profile through Visual Studio. For this example mine is called Release. this will create you a Release.pubxml file in a folder called Publish Profiles, under your project, check this into source control.

Then in your build definition, under the process tab.
Expand the 02. Build > 5 Advanced or similar depending on the version of TFS you are using, add the following to the MSBuild argument text box
/p:DeployOnBuild=true;PublishProfile=Release
ensure the PublishProfile has the same name as the one you created earlier (Release)

this will create your deployment package as part of the build