The toolserver provides Subversion hosting for users, but you have to request the setup of a repositories at Jira first. If your username is jsmith, your svn repository is located at https://svn.toolserver.org/svnroot/jsmith. Before you can use it, you need to run setpass on one of the login servers, to set your LDAP password. You will be asked for this password the first time you commit something, after which the client will remember it and not prompt you again.
By default, only you have access to commit to your repository, but everyone has read-only access. If you want to change this (to make some parts of the repository private, or to allow additional users to commit), file a request in JIRA.
Multi-maintainer projects will have their names prefixed p_, so the url will be https://svn.toolserver.org/svnroot/p_<project name>.
svn is used to access subversion from the command line. A list of the available commands can be obtained via
svn help, while
svn help COMMAND describes a specific command. The O'Reilly book Version Control with Subversion, available online under a CC-BY license, gives a more thorough introduction.
This is an example of using the command-line 'svn' client. If you prefer, most platforms have a GUI subversion client available (e.g. TortoiseSVN for Windows).
To check out a repository into the current directory:
$ svn checkout https://svn.toolserver.org/svnroot/username
(If your local username is different from your Toolserver username, use a URL like https://email@example.com/....
Now you can make changes to the checked out repository. If you add any new files, you need to add them to the repository:
$ svn add newfile.txt
When you're done, commit your changes:
$ svn ci
This will upload your changes to the repository.