Under the "Tools" drop-down menu, you'll find "Seed Swaps." Also here:
https://garden.org/apps/swap/
Review the active swaps (and their guidelines/rules/requirements) to see if one (or more) fits your situation. Watch the tutorial that Dave put together. The link is in the greenish box on the main swap page, though it's easy not to notice:
https://www.youtube.com/watch?...
And, most importantly, have fun