I'm using Bluehost as my hosting service for my website and domain.
Step 1: Go to www.google.com/a & select Standard Edition
Step 2: Click on Get Started, enter in your domain name and follow the wizard.
Step 3: Go to www.google.com/a/yourdomainname.com . Get the CNAME to verify ownership of your domain and activate Email.
Step 4: Log into your hosting provider Cpanel.
Step 5: Go to DNS Editor, select domain name and Add/ Edit the following CNames:
Name: Unique Google String Cname: google.com
Name: mail Cname: ghs.google.com
Name: sites Cname: ghs.google.com
Step 6: From CPanel go to MX Entry, select domain name & add following MX records w/ following priority:
MX Server address & Priority