Here is an easy way to model using transparency so you can see a

reference image in the background:

1. Make 2 layers.

2. In layer 2: Document/Import/"bkgrnd pic".

3. Set Render/Flatten off.

4. Set Draw/"RGB Intensity" to under 70.

5. Pick a material with a transparency setting. Then set

Material/Transparency to 100.

6. Pick Tool/Zsphere. (Make sure draw size = 1.)

7. Now in layer 1 you can draw out your Zspheres and model.

Attached is my recorded Zscript showing it in action...