Step 1: find the image you want to use as a template. This can be any image.
Step 2: open the meme generator
Step 3: click "upload your own image"
Step 4: If the image is in your files, click "upload from device." (This may not be what the button says but it'll be something like that.) If the image or the image URL is on your clipboard, select the text box and do ctrl v.
Step 5: click "allow this template to be shared publicly."
Step 6: fill in the text boxes. The title is necessary for people to find it. You don't need alternate names but it will make it easier for people to find. I personally don't put descriptions or alt names on my templates.
Step 7: click "upload"