I will talk you through it because it is a useful thing to know.
Go to 'Plant Database' (tab on the left). Then the fourth line will say 'Add a new plant to the database'. Click on that.
Then fill in as much as you know.
In this case Primary common name is Epiphyllum
Accepted botanical name is Epiphyllum
Cultivar is Philippe Soulier (I verified the spelling of the name for you)
Then - you're done. Click on 'Proceed to step 2' and follow from there on. The moderator for the forum will approve your entry. After that you can add your pictures.
Oh and all this gets you acorns