I've chosen 'svnrepo' as the user, and 'svnusers' as the group. Users that want to use the repo will need to be added to 'svnusers'.
Set the default group of user 'svnrepo' to 'svnusers'.
Add the 'svnusers' group to any users that need to use the repo.
Switch the the svnrepo user.
Choose a repository root directory, all subversion files will exist inside here.
svnrepo@turtle:~> svnadmin create /home/svnrepo/demo_project
use chmod to change the permissions:
svnrepo@turtle:~/demo_project> chmod g+w db svnrepo@turtle:~/demo_project> cd db svnrepo@turtle:~/demo_project/db> chmod g+w rep-cache.db txn-current-lock transactions/ txn-protorevs/ write-lock svnrepo@turtle:~/demo_project/db> chmod g+w -R revprops/ revs/