How can I upload for example a jpg-file with the api?

I get creating a file from a from a base64-encoded dummy-string to work perfectly:

However for the endpoint upload I get "Path is required". I try /test, /test/test.txt etc but get the same error.

I'm not even sure what to put in the field "conten"t yet, just trying to get ok on the path first.
Ultimately I would like to upload for example a jpg-file. How would one accomplish that?
Swagger just says

and doesn't really advice or give example of how to use it or the difference between creating and uploading. :)