Hi Mary,
The resfit command only works on amino acid sequences. You can look at the density around specific residues using the Zone mouse mode in the "Right Mouse" toolbar. You click on residues with right mouse button (or Command-click on Mac) and it shows just the residues and density nearby and labels the residues. Here's an example
open 7tzt
open 7tzt from eds
ui mousemode right zone
# Command-click on and atom of residue 89
Clicking on an atom and dragging up or down makes the zone shown around that residue larger or smaller.
Tom