Add instructions for creating a pull request

css/site.css

@@ -2,3 +2,7 @@
     max-width: 100px;
     max-height: 100px;
 }
+
+.container img {
+    max-width: 100%;
+}

tools/_posts/2000-01-02-github-cheatsheet.markdown

@@ -9,6 +9,32 @@ layout: course_page
 
 ## How to submit a pull request
 
+To submit a pull request, go to a repository that you forked. Ex. "https://github.com/yourusername/repositoryname/"
+
+Select the "Pull Requests" tab.
+
+![]({{site.baseurl}}/img/tools/github-pull-request-step-1.png)
+
+Click on "New pull request".
+
+![]({{site.baseurl}}/img/tools/github-pull-request-step-2.png)
+
+See if the changes shown are correct and then click "Create pull request".
+
+![]({{site.baseurl}}/img/tools/github-pull-request-step-3.png)
+
+Fill in a title for the pull request and click on "Create".
+
+![]({{site.baseurl}}/img/tools/github-pull-request-step-4.png)
+
+You are done and the pull request will look something like this:
+
+![]({{site.baseurl}}/img/tools/github-pull-request-step-5.png)
+
+You can click on the "Files changed" tab to see the changes that was made.
+
+![]({{site.baseurl}}/img/tools/github-pull-request-step-6.png)
+
 ## How to upload an image
 
 ## How to create a new repository