Hello Rosie and Welcome to ATP!! I'm originally from the east side of Detroit, so I know your area (downriver)
In answer to your question - the way I know to do add a plant is by going to the database for the plant you are wanting to indicate that you have, or want, scroll down to a link on the left hand side of your screen, it is a little blue box which says 'add this plant' Click on the box then a window opens which says 'Status' above a window with 4 options - 'Choose from below', 'Have', 'want', and 'used to have' if you select 'have' there will be 2 options 'available for trade' or 'available for sale'
I hope this helps - let me know if you don't understand!
Cheers and enjoy this website! I've found it to be so much fun!
