You cannot start an entirely new project here. You may only start a new-language version of an existing project. If you want to start a new project, go to meta:proposals for new projects, or see Wikispore if you want to create a test.
Please respect the naming conventions for the test language, to help future migrations of pages to an actual wiki project. All of your test pages (including templates and categories) need to be named uniquely (by using a prefix) and consistently.
How to contribute to a test wiki on Incubator
If you have knowledge of a language which currently has a test wiki here, you are strongly encouraged to contribute to that test wiki.