Howto create Custom part (pot)

Hi,

I am very new at fritzing.

To complete a project I need a custom made part.
I tried to use the parts editor but I do not know how to start a new item.

2nd attempt was to modify a already existing item.
Using inkscape I was able to success some steps but at the end “copper layer” was not defined.

Can sombody help me to create “BOURNS 3266W”?

THX
Cappy