1. Setup SSH client parameter for TortoiseSVN
Right click on the blank of the folder, go to TortoiseSVN->Settings->Network->SSH, find your SSH client here. Actually TortoiseSVNPlink is enough. If your depot has a specific port, put a parameter like "-P XXX" after the binary path of SSH client.
2. Checkout your project folder
Go to the folder you want to checkout your depot: right click on the blank, click "SVN Checkout...", fill the URL like:"svn+ssh://Username@domain/folder_if_applicable"
You are done.