This namespace user:j:jan001:* and it's content (pages, images, …) is reserved for your own usage (only superusers can also access to it)…

• To create a page inside this private space, simply use the standard link syntax without any namespace :

[[example page 1]]
[[example 2|My example page 2]]

• To create a sub-namespace, simply indicate the new page's full position :

[[user:j:jan001:<sub-namespace_to_create>:example 3]]

Feel free to remove this paragraph (beside the title)…
Now, write something!