Twitter Help Please

I signed up for Twitter yesterday since several authors find this an exciting place to reach readers and network with authors and editors.

I would like to find folks who Twitter and also garden, are authors, agents, editors or who are Christians.

It doesn’t seem set up for subject searches to find people that way.
If you have tips on how I can find Twitterers with common interests, let me know please.

At Twitter I am TerraGarden, if that helps.