Newb here : ) Help with a forced dimension, and copying a sketch to a parallel plane

[Redeyejedi]

hi, new here.
hi, new here
i am trying to make a table.
i have run into two problems so far, and they are probably an easy fix, but as stated, still learning.
i have a dimension from the divider's plane to the inner face of the structural members that is supposed to be 6.00 inches. there seems to be a relation preventing me from dimensioning that plane as i'd would like to: 6" from the support faces.
secondly, is there a way to copy the sketch the makes the divider, to also make the sides from that sketch


thanks



EDIT:
nevermind