well smoothing is best done in 'faces sub-object edit mode" Scroll down and you will see a block of buttone under "Surface Properties". most of these buttons as you will see are # 1-32.
what you do to smooth is one of two things, if you have a single object model and you want the whole object to be evenly smoothed you can box select all the faces in that object and click on "Auto Smooth".
here my F-16 unsmoothed

here it is all faces Auto Smoothed.

the other thing, if you want to create say the effent of a crease in the mesh, then you can select a group of faces and then click a numbered button to smooth only those faces together.
these faces are smoothed as Smoothing Group 1.

then select another group along side the previouse to have them smoothed seperatley. These faces set as Smoothing Group 2

and the result, you can see a more profound defference between the to groups and a really big difference between the groups and the faces that arnt smoothed.

later when you want to view what faces are grouped together you can click on the "Select By SG" button then in th epopup window select the groups or groups.
Remember that the smaller the angular difference between faces the less of a difference your going to see between grouped faces, like if the adjacent faces of to groups is flat or nearly flat to each other then they may look smoothed together anyways.
hope this helps
