"Stubs" are articles that need the most help, edit them!
You can also help create wanted pages and update stale ones.
Uploading images is another really easy way to help out! - Start uploading!
You can find a list of useful templates in the templates page.
If you would like more help, visit http://www.blenderguru.com. They have lots of free turtorials and competitions if you are somewhat experienced at Blender. If you would like to learn even more to better yourself at Blender, then Blender Guru offers paid courses such as the Architecture Academy (where you learn how to make photorealistic architecture scenes).
You could also visit the YouTube counterpart of the website: https://www.youtube.com/user/AndrewPPrice. Here you can subscribe to him, but you will not be able to see what competitions are going on at the moment. Basically, his YouTube channel only contains his turtorials and speaches. I would reccomend blenderguru.com instead.