Where is>Source file

[djdesignsco]

I am a dang newb/blind/slow/half asleep, and very very new to the fiver operations, but i can not for the life of me find the SOURCE FILE checkbox to offer it during my sale? Can i get a picture or something to my inbox with an arrow point to it to smack me in my face?! I am active right now so asap would be great if not ill check tomorrow. thanks in advance!

[djdesignsco]

can i please get a quick response anyone please???