Access google contacts for codeigniter applications

Good Morning. I have a codeigniter application and I want to access google contact api with oauth solution . I have a database which the application uses. I want my application to make new entries and changes in google contacts when it does so in the database for according to what user does in the content management system(cms) site.

My CMS is on a server with a specific IP.

At the moment, I have looked at the following site for help: http://ift.tt/1hMhmYa

I am a bit confused at the moment: 1)Steps 2 to Step 7 have been finished 2)For Step 1, what is its purpose 3)where to put oauth.php in my xxxx(codeigniter) folder 4)What is the url for my file like - for my cms system url is (ipaddress/xxxx/index.php/login) 5)By the way,what is javascript origins - i set it as http://localhost/

Please help me. It is a really important task and I am new to web and Google APIs. Thank you very much.