My question is completely explained in the title XD
I want to know for making a new repository in server (not a local repository) I must be the admin ?
You must have the Owner Permissions in order to install a new tool.
If you have this Permission you can go to Admin->Tools and Add an SVN repo from there.
If you do not have this permission, then you must ask the owner of the space.
Further Documentation is here: https://articles.assembla.com/using-subversion/getting-started/get-started-with-svn