You can’t create a branch from a root directory. At the moment you have your repository located at the top level directory, ‘/’ - and are trying to make a copy of that into itself ‘/branches/...’. Subversion does not like that as every its basically trying to copy into itself and make a new revision.

What you need to do is:

1. Create a ‘/trunk’ folder
2. Move everything (except ‘/branches’) into the ‘/trunk’ folder
3. Make branches, which are essentially “copies” from ‘/trunk’ into '/branches/...'