Please make sure you are using Chrome and have Tronlink installed. Your Artist name is your wallet name.
Make sure you have some Tron in your Tronlink wallet. Each transaction uses 411 in Bandwidth and around 200,000 Energy. You can rent Energy, or you can freeze some of your Tron to get free Energy.
To make an NFT first you go to https://pixelmart.io/create.php
or click on the Create button at the top of the page, Upload your image and fill out the form.
Specify if you want to sell your NFT now or later by selecting Yes or No.