Planetminecraft actually just made it's very own Skin Software that's free to use, and really easy to understand :D just go to: https://www.planetminecraft.com/pmcskin3d/ and then click in the left corner. Under the "Files" section there will be a "Get skin from username".

Click that and type in your username and your skin will appear, then correct the mistake and Download your own skin again.

To get the new skin on you can open up you Minecraft Launcher, and go to the "Figures" section and then simply choose the skin. Upload it through there and boom! Your skin has been corrected :D

I see you used PMCskin3D to create your skin. To edit it again, you will need to download it and save it to your computer. Then you need to open PMCskin3D, go to file > open file and open the skin file you just downloaded in the program.

Then you make your edits and when you're done, click file > save to file to save the skin to your computer. Then you go to your skin submission on PMC and click "edit submission" to update the skin. You will have to "edit media" and uploaded the repaired version of your skin from your computer.

First off, which skin editing software ( or website) were you using? Most of them have an option to search up a player’s skin by their username. If your editor has that,Try this : Search up your username, and select the skin. Usually there is an option to save this skin. Save it, and you should then be able to navigate to it and modify it. After that,simply edit it to your liking, select Export, and, if given the option, choose To PC or Mac. Finally, just fill in your Minecraft credentials (If you set up your account with your parents and don’t remember either your email or password, check with them. If you can’t get your password, you’ll have to reset your password.If you can’t get your email, visit Mojang Settings and from there change your email.) and you’ll be all good. Let me know if you have any questions, and any feedback would be welcome. Thanks :)

how did you make it? if you used nova skin you can just click upload skin and it will reimport it and you can edit it