Hi & welcome! You've come to the right place. You can make a free plant list on this site. Inside your list, you can add categories to help organize plants, like "in the back" or "to divide in the spring" or whatever your designations or to-do list might require.
To make your list, find each plant in the database:
https://garden.org/plants/
Once you have clicked on a plant, you will see an "add to list" button.
To access your list later, click on the person, upper right corner, select "your profile" and scroll down to click on your plant list.
If you want, you can look at my plant list to see the various categories I have. The "summer grounded" category helps me remember which plants I've put in the ground as part of the landscape while it's warm outside, and that I need to put those back in a pot or they will be killed if left outside all winter.
https://garden.org/lists/view/...
You can also add personalized notes for each plant.
For some cultivar plants, you may never be able to determine which cultivar you have. For those, you can add the species or genus to your list, and your notes can help remind you which plant you are tracking with those entries.
If you need a plant ID'd, you can put one or more pics of it in a new discussion in the "Plant ID" forum and somebody should recognize it.
Hope that helps you get started!