Then you need to download hammer 3.5 or 3.4. I recommend 3.5, but some others still like 3.4. 3.5 will show models that you are using if setup correctly. You will need to also get a copy zoners compile tools. When you start hammer you will prompt to point to they tools for compiling and you will need an FDG file so the editor now what entities you want to put in. You google for most of this stuff up. Start with that and post back if you need more help.
http://csm2.net/mapping_tools.php
