It is that simple. Just reply right here, paste your entry image into the reply and add a category (pure/open/non-competing). A title and some info about the entry would be nice - but that is not mandatory.
You can find a lot of examples in previous entry threads - like this one:
Just reply right here, paste your entry image into the reply and add a category (pure/open/non-competing). A title and some info about the entry would be nice - but that is not mandatory.