Hi
Welcome in!!! :))
You might have spotted people talking about this
https://wiki.documentfoundation.org/Documentation/Development#Contributors.27_Guide
being a little out-of-date but it's still quite excellent.
Hopefully someone will soon give you an ODFAuthors login and help guide you into working on something useful unless you already have decided on what your mission is going to be. Many people join projects because of a specific thing they want to see fixed. It's a good way in.
Are you keen to work on the guides themselves and if so which of the apps/modules interests you most? (Writer, Calc, Impress?) There is a wiki-Faq that could usefully be translated from French, or the Base Handbook translated from German, or the main Base Guide still needs more people as it is being written from scratch. If you are comfortable working between Xml tags then the in-built help could use a few people to translate it from geek and check for the types of thing proper documentation experts normally check for to smooth it out.
Writer and Impress are being worked on at the moment so it might be good to join in with the people working on those in order to help them get through the process, either reviewing, proof-reading or whatever is needed next for whichever chapter and then move on to being the main author updating a particular chapter.
Anyway, welcome in! I'm just a lurker here but hopefully i might have got things about right for once.
Regards from
Tom