Checkout
Checkout: Create a folder for the repository or module you want to check out, open it and then right click and select "SVN checkout".
Checkout: Insert the url to the repository, and click on "OK". The repository in the image is the whole source tree (see using SVN), if you want to check out a single module, type the name after /trunk/
Checkout: A status box will open showing the progress of the files being checked out.
Checkout: When finished, click on "OK".
Commit
After you have made some changes, and want to commit, do the following:
Commit: Right click in the directory where you have the repository or module checked out and click on "SVN Commit".
Commit: You will be asked to type a log message, type something informative or funny and click on "OK".
Commit: If this is the first commit you have made, you will probably be asked to enter your username and password for SourceForge.
Commit: A dialog box will show the progress of the commit, when it is finished, click on "OK".
Update
Update: Right click in the folder in which you have the SVN repository and click on "SVN Update".
Update: Wait until the dialog box has completed.