Added git commands reference to README

README.md

@@ -26,4 +26,40 @@ A simple game where the computer picks a number and the player must guess what i
 * Multiplayer: play with two humans
 * Spectator: play with two AIs
 * Menu: select between different game modes
-* Build a GUI 
+* Build a GUI 
+
+## Contribution 
+Add the files you changed:
+```
+git add ngg.php
+```
+
+Commit the new changes:
+```
+git commit -m "Fixed syntax error"
+```
+
+Push the changes
+```
+git push
+```
+
+Get the latest code
+```
+git pull
+```
+
+See the changes you've made since your last commit (press Q to exit if it's long enough to scroll)
+```
+git diff
+```
+
+See which branch you're on now
+```
+git branch
+```
+
+Switch to a different branch to see that language's work:
+```
+git checkout php
+```