If you want to have mail server alone with google for your domain, You need to visit the URL
http://google.com/a
Once you got the MX, cname records from the google, You need to add those records in the DNS settings of your domain in the hosting control panel.
Please follow the below procedure to set up DNS for google Apps
1) Login to your WHM
2) Under DNS Functions link, click on Edit DNS zone
3) Choose the DNs Zone to edit
4) Click on Edit button
Add the new records under “Add New Entries Below this Line”
5) Point the MX entry provided by Google – (Select MX from drop down menu) Enter the MX record in the text box against MX
6) Point the cname provided by Google – (Select CNAME from drop down menu) Enter the CNAME record in the text box against CNAME
7) Remove the MX and mail CNAME record which is pointing to our server.
8) Change the mail router to remote mail server at the end.
9) Click on Save button.