This would depend on the scope and scale of the garden with consideration to the quality of the gardening site, what will be grown, how many gardeners will be participating and the accessibility concerns of participants. Starting with the basics such as soil, seeds, mulch, starter plants, raised beds, and hand tools (fork, spade, trowel, shears). Linked below are a few different courses and guides for starting a community garden and container gardening:

https://extension.missouri.edu/publications/mp906

https://extension.purdue.edu/cdext/thematic-areas/community-planning/grasstogarden.html

https://u.osu.edu/growingfranklin/2020/04/23/no-garden-no-problem-container-gardening-basics/

The Cuyahoga County Extension office hosts a community gardener training in the spring that teaches garden leaders how to start and maintain a gardening program in their community. Details for the course are available at cuyahoga.osu.edu.