So, I've got the level up, I've tessellated the 2 floor polygons, gone to the edit mesh modifier, selected face and selected all the rows of polygons around the edge of the level which need to be raised to 128 units on the Z-axis.
And here's my problem. They're selected, but at the bottom where the co-ordinates are, the box is greyed out and won't let me type in to change the height.
Yes, I'm a noob at mapmaking and perhaps I'm missing something horribly obvious but I've done a forum search and I've tinkered around with 3dsmax to see if I can figure it out meself like I have with all my previous problems but nothing

Help would be appreciated, thanx in advance.
Edit: I found a way to move all the selected faces by dragging up the z-axis arrow when I choose the move cursor thing, however this isn't very precise. What I don't get is how I can move it yet not enter exactly how much by Oo