How to change skin in Minecraft?

I went on this website for Minecraft skins and found a cool skin that was called the fire wizard but i kinda didn't like it so I decided to edit it. I finished editing and it gave me 2 options: download to computer, and upload to compute. I thought the download one was the thing I needed but it just send some weird picture to my pictures. I dot know what upload to computer would do so I didn't click it. For you guys that are wondering what website I went to i went to was called the Skindex-minecraft skins. Please help and if you can't then tell me a good (McAfee safe/approved) website for getting a skin on my minecraft character. Please Help!

Added (1). Nevermind it didn't say upload to computer it said upload FROM computer. Thats why I didn't click it. Also sorry about some spelling mistakes, this computer is dumb and the keys can't be pressed to lightly.

Log in to your MC Mojang Account and choose the option "change skin".
It gives an option to upload, click that and choose that weird picture from your gallery.
Hopefully that should do the trick.

Login at minecraft.net, go to profile then change skin and upload the weird picture.
Hope this helps!

1.) find a skins website
2.)find a skin you like
3.) do NOT download the skin, upload it
4.)log in with Mojang
5.)boot up Minecraft
6.) Enjoy
7.)if that didn't work and you bought minecraft already, try again until this process works
8.) log into Mojang first then try

You have to login into your account on Minecraft.net and go to your account. There, you can upload your skin picture, which is a wierdly looking picture with all the skin parts there.

Download the skin.

Sign in at minecraft.net

Go to profile and click change skin.

Upload new skin.