You can download the last LWAMI mod from here, just select Downloads from the top of this screen.
LWAMI makes some small changes (mostly to your sonar display) but also updates some of the ship models. The two "new" campaigns (Red Storm Rising and The Liu Doctrine) were written for the LWAMI mod.
One quick tip to installing DW mods- Make sure you are starting out with just the base game (and it works on its own). Also make sure your base game was patched to Ver 1.04 (most of newer DW downloads are already patched to 1.04 but check anyway). The install process is basically easy but there are a few tricks. Unzip the Mod folders/files to your DW install. Find the "install" program and click it, the install process should begin. MAKE SURE THE INSTALL PROGRAM RUNS FULLY. Mod installs for DW can take a while, even on a new computer (we're talking 5 to 8 minutes for the larger mods like LWAMI and RA).
One quick fix to improve graphics can be done by making some manual edits to the
dangerouswaters.ini file. Check the recent posts and threads in these sub forums for more info, for the most part you'll want to change Graphics Mode to "3", avoid "Mode 4"- its always been unstable. You'll need to know how to do this manually if you use the d3d8.dll file to run the game.
Meanwhile, welcome to the game.
Dangerous Waters can be frustrating to learn, but you can learn it without too much trouble.