All HOWTOs and other LDP documents are copyright by the authors so the LDP doesn't have any special rights to your writing. We only accept documents that have a license which permits anyone to copy and distribute the document. We encourage authors to also allow modification in their license. This way, if the author stops maintaining a document, someone else can do so. For more details see our Manifesto.
If you are not sure what to write about, take look at some of LDP's documents including the ones in Unmaintained HOWTOs. Pick a topic you're interested in that needs good documentation. If you find something already written and maintained that needs improvement, try to contact the author, first and make suggestions. If you can't reach the author, look at the license and see if you're allowed to modify the document. But even in the cases where you are not allowed to make modifications and improvements, you can just write a new document on the same topic from scratch, using a new outline new sources of information.