I have them all but I do not know how to trigger this achievement. Please advise me

If you have them in your wardrobe, go to your wardrobe, and click on 'Items'. Let the page load, then click 'Back to Subeta'. Check the Achievements page, and after that, you'll get the achievement on the top of whatever page you visit next.

Thanks so very much. Off to give it a try. Judy