I'm not sure we have speed dial anymore. But instead of speed dialing, you can create a direct dial icon on your home screen - tap Menu, Add, Shortcuts, Direct dial, then find the contact you want. If a picture is assigned to the contact, it will be used as the icon. Now anytime you want to quickly dial that person, just tap their picture. It's fast and you don't need to remember who's on which number.

You can also create direct message icons, or a link to a contact so you can select which method to use for that contact (call, text, email, etc.).

I'm not sure you can do it on the phone. Normally you'd sync with your gmail account where you assign groups, etc., and then sync with your phone to update it.