So you have made the sig? And you just want to use it?

If thats the case, you should be able to save the image as a gif (if you save it as a jpg the transparent background will come out white) in the program, I'm not entirely sure how you do this, as I dont use that program but I'm sure theres a way!

With photoshop, when you click save it'll come up with a box asking where you want to save it too, then under the part where you name the file theres a drop down menu of all different file types, so then you select gif and it saves.....See if Picture It! is the same.