You can use GitHub itself for Graphic design below are some examples:-
You can upload a PSD(PhotoShop Document) of an image you want to put in the public domain.
Anyone can watch that image and be notified when you make changes to it.
Other people can also submit a pull request with the changes that they have made to your image, and you can decide whether to accept them or not.
Within the bounds of the license anyone can download the PSD and use it.
The changes that you or any other has made in the image can be seen by anyone including the history or progression of the image.
If you want to know more about GitHub whether if you are an absolute beginner or you have a little knowledge of GitHub in that case to learn GitHub and all its concepts such as pull request or creating a repository in detail which is necessary for a programmer you can learn it by taking up the GitHub training course. If you like to read then you can have a look at the GitHub tutorial. If you want to learn it by watching the video tutorial then you can have a look at the following tutorial:- .