Doc for contribution

README.md

@@ -49,4 +49,3 @@ Piwigo is widely driven by its community; if you want to improve the code, fork
 ## License
 
 Piwigo is released under the GPL v2 license.
-

docs/CONTRIBUTING.md

@@ -0,0 +1,71 @@
+# Get the Piwigo project
+
+## Prerequisites
+To contribute to project, you will need to install on your computer [Git](https://git-scm.com/) and to have a [Github account](https://github.com/join?source=header-home).
+
+If you don't really know how to use git, I will recommend you to check this [guide](https://git-scm.com/book/en/v2/Getting-Started-Git-Basics). If you are comfortable with git and GitHub, just go to "Create a pull request" section.
+
+### How to configure Git
+
+To add associate your GitHub account and your Git, you will need use this command on Git Bash:
+
+- Set up your name:
+`git config --global user.name "Firstname lastname"`
+
+- Set up your e-mail address:
+`git config --global user.email "email@example.com"`
+
+### Get the project on your GitHub account
+You have to click on the fork button of the [Piwigo GitHub](https://github.com/Piwigo/Piwigo).
+
+![Lien](HowToFork.png)
+
+### Get your forked project on your computer
+Go where you want to work on the project (for example in your **www** folder) and enter this command (Don't forget to replace `username` with your GitHub username):
+
+`git clone https://github.com/username/Piwigo`
+
+## Create a branch
+
+To avoid conflicts when updating your fork from the upstream, always work on a branch (from `master`).
+
+```
+git checkout master
+git checkout -b issue-496-group-deletion
+```
+We recommend explicit name for your branch, such as `issue-<id>-<short-summary>`
+
+Now, you can work on your new branch. Modify code, test your changes and commit locally. For each commit, prefix your log with the id of your issue, for example: `issue #496`. This will help the Piwigo team by automatically binding your changes with the issue.
+
+Update your GitHub repository:
+
+`git push origin <branch>`
+
+## Create a pull request
+
+On GitHub you should see your branch (with commits) that you pushed before like this:
+
+![Lien](HowToPullRequest.png)
+
+Once you clicked the button "Compare & pull request", you have to give a name to the pull request.
+
+![lien](Issue.png)
+
+Example name of a pull request: `Issue 965 manage group deletion`
+
+If you forget something, don't worry: you can continue to push commits on your branch and it will automatically update your pull request.
+
+Now the Piwigo team can review your pull request... and merge it!
+
+## Tips
+
+##### #1
+
+If you had to update your fork because there is activity on the upstream, you can go to this link:
+[syncing a fork](https://help.github.com/articles/syncing-a-fork/)
+
+##### #2
+
+When you finished your work and going to commit the final change. You can specify *Fixes* and the GitHub id of the original issue to help the Piwigo team. This will close automatically the pull request when this will be merged on the upstream.
+
+Example of a last commit: `Fixes #965 Add a new column`