How to change your skin in PC minecraft?

To change your skin for the PC version, you just log into your Mojang account on the Minecraft website & visit the profile page.

At the top of the page will be the skin upload option. You can select the "Male" (Steve) or "Female" (Alex) & you can download the template to work with.

Once you have your desired skin made (as there's various skin editors available online & offline -- http://www.needcoolshoes.com/ is a good online tool) OR copied from a Minecraft skin site… You just upload the skin from your profile page. This can be done as many times as needed, but generally should pace yourself with skin changes (I wouldn't to it more than once a month as it will likely annoy friends & other users. Changing your skin every 3 - 6 months OR LESS is generally acceptable).

As the page states, the latest versions (v1.7.9 onward) should reflect your new skin almost immeidately. Older versions (v1.7.8 through v1.3.1) will take up to an hour to reflect your new skin. "Ancient versions" (v 1.3 or older) may not reflect it until you do a login cycle (log into Minecraft via the launcher). With any version of Minecraft, you will generally need to log out & log back in to see your new skin… Just to be safe.

IMPORTANT: Custom skins are for PREMIUM (aka paid) USERS ONLY! If you have not purchased Minecraft, you will not be able to have a custom skin.

If you want to modify the default Steve / Alex skins for offline (for copies of Minecraft that can't connect to the server), you can modify the default skins within the game's files, but that changes the default for skin for EVERYBODY playing that copy of Minecraft & is generally not recommended.

HOpe this helps!