Subversion uses edit-commit cycles. So, you follow this procedure:
- create an import folder somewhere with the following structure:
import
|-- Branches
|-- Tags
|-- Trunk
In the Trunk folder, you place the sourcecode you want to have under sourcecontrol. You then right click import and select tortoisesvn -> Import... You then specify the repository to import, and it gets imported.
You now have the source in sourcecontrol. But you want to edit it, so you 'checkout' a folder in the repository, normally a trunk folder. So you create a folder in where you want to work (can be your original folder, first clean it) and right click there and select Check out. Select the trunk folder of the code you just checked in and click OK. The code is added to the folder.
You can now edit the sourcecode in whatever editor you please. After you're done, you simply rightclick the folder and select Commit. You should just check the files you want to checkin, so bin and obj folders shouldn't be checked. You can exclude them later in the tortoise menu
From then on, you just edit and after you're done, select commit. It's wise to type a message each time you check in with what you've done, so you get a nice log.