In photoshop when you click on File>New it gives the option of white, background color or transparent.
I use mostly Illustrator and I'm not familliar with Picture It at all. So disclaimer- I am not a photoshop guru- just trying to help
Soooo- here are a couple of options that I THINK will work and I'm sure that there are umteen more ways to do it.
1. Select the white bg with the magic wand then Select>Inverse then cut and paste that into a new file (File>New) and select transparent
OR
2. Select the white bg then Select>Inverse then save as .png
HTH
And anyone else feel free to correct this or help
