Idk what going on I downloaded and idk how to do the deck or anything haha my mind just got blown away
You have to download the card database first. Then, you should be able to click on the "Deck Editor" tab, hit "New Deck," and a search bar and a list of cards should pop up if they weren't already there. You type in the name of the card in the search bar, and it should appear in the list below. Click on the name and hit "Add to maindeck," "Add to sideboard," etc etc. Then, you just click on "Deck Editor" again, hit "Save Deck," name it, and it will be saved for whenever you want to play with it, change it, etc! :)