To see measurements in the editor screens, make sure you have the measurements button enabled - in Shaper it is to the left of the pencil button on the right panel:
In Blocker it is the on top right of the group of buttons:
In Shaper, you can set the size of a particular shape by tapping on the box with the writing on it for any of the axes:
Hope that helps! Let us know if you have any questions!