Thank you very much Matthias!
I have VS 2005 pro. And yes I have Microsoft Web Application Projects (WAP).
I don't know if I have fixed well all the liking paths. I guess not because I get the next error when I start the debug (F5):
"Unable to start debugging on the server. The web server is not configured correctly..."
In the IIS I have "localhost/DNNPortal" so, I have modified the next properties in the DotNetNuke.Forums.build file according to my environment:
<property name="rootWeb" value="http://localhost/" overwrite="false" />
<property name="webAlias" value="DNNPortal" overwrite="false" />
I have also checked this properties in the DotNetNuke.SubProject.build file, which I don't know if I have to modify the words in bold:
<solution solutionfile="..\..\Solutions\DotNetNuke.All\DotNetNuke.All.sln" configuration="${project.configuration}">
<webmap>
<map url="http://localhost/DotNetNuke/DotNetNuke.vbproj" path="..\..\DotNetNuke.vbproj" />
</webmap>
</solution>
<solution solutionfile="${subproject.solution}" configuration="${project.configuration}">
<webmap>
<map url="http://localhost/DotNetNuke/DotNetNuke.vbproj" path="..\..\DotNetNuke.vbproj" />
</webmap>
</solution>
The thing is that I don't find the DotNetNuke.vbproj. I have found the this file: DotNetNuke.webproj.
Am I skipping any other change?