Well,
Wikia let's you make wikis so you could use that. (Mind you that I've never created one.)
When it comes to getting your game out, well, what's wrong with our Progressing games and Games Showcase. Posting in the Showcase threads also gets attention. Plus, you can make a banner for your game and stick that in your signature.
Website design is a bit bigger, but doable, though I don't know of any places to host it. But check out
W3Schools, they have great tutorials and references on all things websites. (You probably only need HTML, CSS, and maybe some JavaScript.)
Scripting is a bit tough for me to explain because it's pretty different depending on what your working with. Assuming Pokemon Essentials, Scripting is done in Ruby.
Codecademy,
Tutorialspoint, and
RubyLearning are good places to start. And you should try reading the code already there and try to understand what it does. That really helped me.
Finally sprites. This really depends on the style of sprites you're going for. Each generation has different styles for both battle and overworld sprites. Default essentials looks like Firered/Leafgreen, so I would recommend
Chesu's Spriting tutorials. Of course, just as with scripting, take a look at the other sprites in the same generation to get the feel for how they are put together.
