Welcome to the forum Nathan. What's your interest in the Civil Air Patrol if I may ask? My two collecting obsessions are rations and Civil Defense Administration items so I'm just curious if you or a family member participated in the Civil Air Patrol or what your take on it was.
To answer your question about PMs, when you're signed in you'll see the PM button under Post/Joined/Location info with the Username on the left. The PM Button is right next to the Spinning Globe button to see where users are on the map. You can also go to User Control Panel (upper left under Board Index when signed in), and then select Private Message from the page that loads and enter one or more users manually. On this forum, many of us will send private messages to each other to set up trades or sales. Keep an eye on the # new messages (right next to the control panel link) to see if anyone on here has been sending you offers.
So you've told us you're in Las Vegas, that definitely helps. Can you give us an idea of what you have already and what you're looking for or at least what you're most interested in finding? As I'm sure many of us would tell you, eBay tends to be our best bet for finding rarer items. Personally, I have a set of saved searches that I check now and then for new items and good deals, but there is always something on there, especially if you're new to this and have a ton of gaps to fill in the collection.
If you're lost and don't know where to begin, start browsing through the Ration Talk subsections - they're more informational than say the Reviews section for the most part. Download a Operational Rations manual like
this one (not classified or restricted) and get familiar with the history of ration development in the US. Keep an eye out at yard sales, flea markets, antique stores, etc. Good luck!