i have different kind of Tshirts,shirts and jackets of .fbx type and i am having a 3d man also,now what i want i want is on the press of a button i want to put these different kinds of shirts,tshirts,jacket on him.Please guide me how to do this in unity 3d,i have searched everywhere but i am not getting proper step by step method to implement this.Please let me know proper method to implement this.
If you are using Unity Pro there is a free asset by Unity itself called Character Customization that you can use rather than doing things from scratch which is tedious.
You can also search for other assets on store if you like.
OR
You can also check out this tutorial Customizable Characters in Unity
I answered this question twice in the last few days so instead of writing it all again, you can just check out the latest accepted answer 