I'm not Vegas but I could answer it, too^^
Make a thumbnail of your screenshot.
You can use any tool to resize an image.
I used
IrfanView and resized it from 950px × 594px to 320px × 200px.
Code is:
[url=link of full image][img]link of small image[/img][/url]
Other method:You simply use the thumbnail function of an image hoster - for example ImageShack.
(My 2nd picture was created by it.)
Greets