Hi Shaikh, if you want to make a specific point mutation, you are going to need to proceed with homology directed repair..for that you will need to inject a donor vector along with your cas9..
i like this protocol: http://www.nature.com/nprot/journal/v8/n11/full/nprot.2013.143.html
just follow the homology directed repair methods..
I was going to say check out Addgene's CRISPR guide which has lots of protocols but Kai beat me to it--thanks for spreading the word! Our nonprofit only makes it when scientists support Addgene. Note, and you can call an Addgenie to get advice on choosing a vector if that would be helpful.