This is a simple tutorial to start editing levels.
First of all some usefull infos about level creation.
Level life cycle:
1) You create a level with at least one slingshot and one target.
2) Play your level and complete it (if your level cannot be finished it won't be able to be uploaded).
3) Go to the editor menu saving and click on the action->upload button.
4) Now your level will be analyzed and if it is accepted it will be available for download in the play menu.
5) Check the status of your level clicking the update button in the editor menu.
Be careful that for every minimal change you did in your level you have to play your level and finished it again. This is a little constraint to avoid uploading impossible levels.
This is the video tutorial: