Go to the official Minecraft website and sign in with your Microsoft account
Open your Minecraft profile or account settings
Select the skin or profile customization option
Upload your skin file in PNG format
Choose the skin model type if prompted
Save or confirm the changes
Launch Minecraft and log in with the same account
Wait for the skin to sync in-game
If needed, restart Minecraft to see the new skin
For Minecraft Bedrock Edition, open the Dressing Room from the main menu
Select Edit Character or a custom character slot
Choose owned items or import a custom skin if supported
Save the character changes
For Minecraft Java Edition, use the Minecraft website profile page to upload the skin
Make sure the skin file matches the correct size and format
Check that you are using the correct account linked to Minecraft