Basically iCloud will do it for you.
All you have to do on your iOS devices is login to your iCloud account and enable mail synchronisation, iCloud will do the rest.
Your profile states that you are using OS X 10.5.8, which cannot run iCloud. If this is the case, you can still use iCloud mail, but will have to enter the details manually.(iCloud requires OS X 10.7.2 or better on a Mac)