added new doc about creating MR

doc/gitlab-basics/README.md

@@ -19,3 +19,5 @@ Step-by-step guides on the basics of working with Git and GitLab.
 * [Fork a project](fork-project.md)
 * [Add a file](add-file.md)
+
+* [Create a Merge Request](add-merge-request.md)

doc/gitlab-basics/add-merge-request.md

+# How to create a merge request
+
+Merge Requests are useful to integrate separate changes that you've made to a project, on different branches.
+
+To create a new Merge Request, sign in to [GitLab.com](https://gitlab.com).
+
+Select a project on the right side of your screen:
+
+![Select a project](basicsimages/select_project.png)
+
+Click on "Merge Requests" on the left side of your screen:
+
+![Merge requests](basicsimages/merge_requests.png)
+
+Click on "+ new Merge Request" on the right side of the screen:
+
+![New Merge Request](basicsimages/new_merge_request.png)
+
+Select a source branch or branch:
+
+![Select a branch](basicsimages/select_branch.png)
+
+Click on the "compare branches" button:
+
+![Compare branches](basicsimages/compare_branches.png)
+
+Add a title and a description to your Merge Request:
+
+![Add a title and description](basicsimages/title_description_mr.png)
+
+Select a user to review your Merge Request and to accept or close it. You may also select milestones and labels (they are optional). Then click on the "submit new Merge Request" button:
+
+![Add a new merge request](basicsimages/add_new_merge_request.png)
+
+Your Merge Request will be ready to be approved and published.
+
+### Note
+
+After you created a new branch, you'll be able to find a "create a Merge Request" button at the top of your screen.
+You may automatically create a Merge Request from your recently created branch when clicking on this button:
+