more informations about commits, tagging and etc.

git_intro.md

@@ -15,9 +15,11 @@ This is Git/Gitlab tutorial for Cogcomp, we assumes that you have already knows
 
 Please make sure you are comfortable to perform commit/push/pull/merge
 If you are not familiar with concepts. There are many interactive git tutorial you can follows, for examples:
+
 * [Code School](https://www.codeschool.com/paths/git): You can try *Try Git* for free but have to paid for the rest of the course. However, I (Hao) highly recommend this Course as the cost is reasonable and the course itself is well-organized.
 * [Git - the Simple Guide](http://rogerdudler.github.io/git-guide/) A very simple guide that covers all the basic things.
 * [Pro Git](http://git-scm.com/book/en/v2) The most comprehensive tutorial you can found.
+* [Git Ready](http://gitready.com/) 
 
 
 ## Git tutorial
@@ -25,11 +27,14 @@ If you are not familiar with concepts. There are many interactive git tutorial y
 Please make sure that you can answer the following questions:
 
 * What is Git
-* what is the difference between commit and push
-* how to merge, and handle conflicts
-* how to view changes
-
+* What is staged changes.
+* What is the difference between commit and push
+* How to commit, push, and pull.
+* How to merge, and handle conflicts
+* How to view changes using git log.
+* How to create/switch branches.
 
+If you can not answer ***all*** the question above, you should go back to the basic git tutorials listed in **Prerequisite** section.
 
 ### Some tricks:
 
@@ -40,12 +45,32 @@ Use alias to make your daily job easier by typing less characters. Here are some
 [http://git-scm.com/book/en/v2/Git-Basics-Git-Aliases](http://git-scm.com/book/en/v2/Git-Basics-Git-Aliases)
 
 ### Basic Git Operation
-### Tagging/Release
+
+#### Tagging/Release
+
+It's recommended to create tags for software releases. this is a known concept, which also exists in SVN. You can create a new tag named 1.0.0 by executing
+
+    git tag 1.0.0 1b2e1d63ff
+
+the 1b2e1d63ff stands for the first 10 characters of the commit id you want to reference with your tag. You can get the commit id by looking at the output of `git log` 
+
+
 ### Commit messages (How to write good commit messages)
 Many developers have discussion ([example](http://stackoverflow.com/questions/2290016/git-commit-messages-50-72-formatting)),  
 
+#### When to commit
+
+Ideally, you should commit once you finished one single basic features. So you change will be traceable and easy to revert.
+
+#### When to push
+
+WHen you are happy with all your new commits, you will be ready to push. Once you push your commits, they will be available online.
+
+
 
 #### Writing good commit message
+A good commit message should 
+
 
 #### Split commit message