Hi designer22,
You are correct in placing the lines in the drawing view but make sure you are placing driving dimensions, and that 'maintain relationships' is on.
The lock icon needs to be on (ie depressed) when placing the dimension then go to Tools > Maintain Relationships (I'm working from memory here so apologies if I'm not quite right).
By default, SE colours driving dimensions black and driven dimensions a kind of green/blue (can't remember what the name of the colour is). Some people change the standards so that they are both the same colour, but I think that's a bad idea.
Alternatively, I think you can use the offset command to offset existing edges from your view.
bc.