is it possible to save your drawings to work on them later?

yes

care to instruct me on how to do it??

To the right of your drawing you will see links, one of them says "revise image". clicking on that link pulls the image up in the applet you used to draw it in the first place and is ready for you to add to it. Assuming you haven't used up the allocated space limit for that drawing)

care to instruct me on how to do it??

after you draw something, click on your drawing either from the welcome page or from your gallery or wherever you may find it. Then you'll see it like this ------> http://www.geocities.com/inky1_2000/example.jpg <------. I've drawn where to look for the link that takes it back into the paint program so you can do whatever you need to do to it.

When you want to stop for awhile...click submit...after the OK box comes on..you will have to enter a title.. some kind of description..a rating...and whether you want to submit it as unfinished HIDDEN.. (nobody can see it until you post it finished)..or just unfinished... (this way they will see the stage at which you submitted it..if you want suggestions or criticism)....then at the bottom ..hit submit..and it should save.... to go back to work on it...do what Axil said...

yeah, all that stuff he said has to happen first. :)