:) Gsketchup :menu window/component/shape/sphere :) (i have it but don't know if it's by default maybe I have add it I don't remember)

For post an image on the forum just use the "Attachment" button for link your image
and then you can (you are not obliged)
copy past the adress image and write
"<img src="adresse image">" without the ""external for see the image in the post it self
it's the same if you have an image from another host