Well this may sound complicated but its not truthfully. Well im sure you all know Mabel an Sable that run the little design shop usually located down by the ocean. Well for those of you that noticed Mabel the Blue looking Hedgehog will always greet you and help you. Her sister Sabeel is always sewing away an is sometimes rude if you try to talk to her. She will say things like "Im busy now" or ask her sister if she can assist you. Well here is where (STEP 1): visit the shop everyday and make sure you speak to Sabel various(many)times after speaking to her for a few days in a row she will loosen up an will have a conversation with you. Now (STEP 2): Make sure to start a friendship with her she will tell you about her past an some interesting stuff. Now after you do this for a while she will eventully give you 5 shirts now after you have the 5 shirts go and sell them to Tom Nook. The next day you will receive a fruit in the mail an now plant it in a well picked place. Now The next day go to Nook an He should ask you what kind of Shop do you want to run. Now the creativity is up to you but wait a week an your shop should be in business! GOOD LUCK. (Tip: when trying to acquire the shirts it may take a while so be patient)