Colors

Good morning,

I developed a very straight forward html page using dreamweaver.  I
spent hours (I'm learning) to get the layout and colors just right.
Now that I have put it in place, a couple user commented on the
colors.  When I saw the page on there PCs the colors are completly
different from that which appears on my laptop.  Why is there a
difference and how can I set it up so what I develop is actually what
the person at the other end will see as well?

Thank you in advance,

QB