To tag an image, open the Edit Album option.
You'll see the 'Tag' icon at the bottom of each image in your album.
The image will open up on the page.
Right click your mouse over the plant you want to tag. (like you'd tag an image on Facebook)
A window will pop up and you can start typing either the botanical or common name of the plant.
A scroll slide will appear and the system suggests possible options.
Select the proper name for your plant and click on it.
That name will appear in the top section.
If your plant has a cultivar name, you can then drill down on the cultivar section and select the plant's cultivar name.
Once that is done, you can click on another plant in that image and repeat the tagging process.
When you're done, click the Done Tagging button at the bottom of the page and save your work.
You can go back in at any point and continue to add tags.