So the first thing you need is to get both of your skins, the accessory, and the base.

Once you have downloaded it you are going to go to this link (piskelapp.com) once you are there, you are going to want to click
"Create Sprite" once you are there you should click "Browse Images" get out the file for the accessory skin and copy it using this tool



Then, you must upload your base skin and get rid of the other one, after you've copied it. and then you simply, paste the accessory onto the skin.



You probably know what to do for the rest, upload it to your Minecraft launcher, and play the game :D


Disclaimer: you might have to delete a few pixels that were on the previous skin so it doesn't overlap, the rolled-up sleeves on my previous skins overlapped lol.

Both of these skins:

https://www.planetminecraft.com/skin/shopmrbeast-com/

https://www.planetminecraft.com/skin/zatom-no-16/