Garnet does not support memory card access yet so you will have to convert .puz files to .pdb. Once you have created .pdb files, you can click on the "Install" button and select your pdb and have it installed to the garnet storage heap.

To delete files from the garnet storage heap, launch a garnet application to start up the vm, hit the home button near the bottom left, and then tap on the top left where the time is or on the menu button on the bottom. There will be a menu item called "Delete". Select that and you should see the pdb files in the list. If you don't see them, you may need to install a palm file manager to delete them.