chmod isn't supposed to give you back any result. do a 'ls -als' and you'll see that the line containing the file has -rwx------ in front of it.

This is how the encoding scheme works:
Those 10 characters represent the access to that file/directory, the last 3 are user specific, the group of tree before those are group-specific, and the three before that are for root only (or the owner of the file, I'm not sure).

r gives read-access
w gives write-access
x gives execute access

So, if the last three characters of that line read r--, the users that fall in that category have only read-access to the file.

What about the numbers, then? RWX is encoded in numbers: R=4, W=2, X=1. Add all the numbers which apply, and there's the number you use:
chmod 735 will result in -rwx-wx-r-x for that file:

7 = 4 + 2 + 1 ( or, R and W and X )
3 = 2 + 1 ( or, just W and X )
5 = 4 + 1 ( R and X )