How to save drawings and upload to continue working

I am fairly new to the site and I love the drawing application. I just finished a drawing I call Snow Rose...it took me almost all day to finish it to where I wanted to post it to the gallery. I tried to post it and thank goodness I didn't close out the window before checking to see if it published right. I can't find it anywhere in the gallery. So I saved it to my computer so I could upload it and try again at a later date. What format do I save the drawing so I can find it on my computer and upload it to try to publish it again? Please help.

is there a certain format that you can load back up after you save to your computer to publish?

You have to save the image as a .dra file. So for example I'm saving an image called mew I save it as mew.dra then I can open it later. Happy Drawing! :D