Meg and I created a SourceForge project for the Image Markup Tool, which is here. After adding Meg as a developer and giving her admin privileges, we set about figuring out SVN. It took a while to get the hang of it, so I'm documenting what I ended up doing to get it working.

Initially, you get an empty repository which is at "revision 0". I checked that out using svn co into a directory on my HD. That process gives you a .svn directory which has configuration and revisioning data in it. The structure is imagemarkuptool/.svn. Then we created a directory structure based on /trunk/, containing a subdirectory for each of our initial sub-projects (which will eventually be combined into the final application). I put that directory, including the code for the initial test project with SVG icons, into the /imagemarkuptool/ directory, alongside the .svn directory. Then I ran svn add trunk to add that directory and its tree to the project; then svn commit to upload changes to SVN. Meg checked out the tree and confirmed the structure is as planned.