How to uploading images from frontend to Deno.serve()

Hey,

can someone please give me a vanilla code example on how to upload files from my frontend application to the server that uses Deno.serve()Deno.serve().
I know how to upload the image in the frontend and send it to the Deno backend using a POST request, but how can I work with this image on the server side?
Currently my backend is set up without any framework.

Thanks!