Hello, Minato. Welcome to Art Castle! Art Castle a community for the artistic and non-artistic people. As you can probably see by looking at the actual forum board, there is a category entitled "Museum." There, we have the Signature of the Week (Or SotW), A Render Gallery (which could be seen when you have 10+ posts), and we have the Graphics page. I'll start at the beginning.
Signature of the WeekThis is where members, whom are Graphic Designers of any kind, make signatures based on the theme that is given to them. Simple, no? In order to participate you need to have a gallery in the graphics section where you can post up to date works.
RendersAnother simple one. Members take a stock image, which is an image that has a type of background, and basically remove that background to make it transparent. They then can put it up in the render submission thread, and if our lovely admin Fred likes it he will give it the stamp of approval. Once that is done, other members are allowed to use those renders for graphic work and such. However, plagiarism will not be tolerated.
GraphicsFor those who would like to post up a "gallery" to show they're works that they have done in an art program. Whether it be Paint, Paint.net, G.I.M.P, Photoshop, or an online type of program. I don't really think making a new topic for every little creation is needed, since it is preferred that you have a gallery to show a few works where other members can give feedback, and you can occasionally update it. And, don't browse others gallery and try using a signature, avatar, etc. of theirs without their permission. Since that would be a form of plagiarism.
We also have a "Off Topic" section, where you can chat about Anime, Manga, Cartoons, Sports, Jokes, Games, Videos, Blogs, Debates, etc. The list is endless! You can also go into our "Other Stuff" section where you can chat about thing that don't fit the category of anything else.
That being said, I will give you another welcome and I hope you enjoy your stay at Art Castle.