There's a lot to know in planting a garden, whether it is your own, a community garden or a school garden. Below are links to several fact sheets provided by UNH Cooperative Extension that cover some of the topics of interest to new or continuing gardeners. You may want to print them out and provide them in a binder for your community garden participants.
Composting, Fertilizing, Mulching
Growing and Caring for Specific Crops
Dealing with Insects and Disease
Where to Find More Help