The best way to learn the ins and outs of Thermonuclear war is to run the tutorial, or watch the rolling demo. Launch the game and click on Tutorial, or Rolling Demo in the main menu. You can also click on the Manual button in the main menu to open the DEFCON manual.pdf for complete instructions.
Place your units and probe your enemy's defenses as the DEFCON clock counts down. When it reaches DEFCON 1, time to let the missiles fly!
Change your viewpoint by moving the cursor to the edge of the screen, or use the w (north), s (south), a (west) and d (east) keys. Zoom in using the q key, and out using the e key or use your mouse's scroll wheel to zoom in and out.
To place a unit, click on the Unit icon in the lower right to bring up the Unit Panel. Choose the unit in the panel, and then click on the map to place it.
To change a unit's active mode, right button click, or press the control key and click on the unit.
To move fleets select them by clicking on one of the ships in the fleet, then right, or control click where you want them to move.
To deploy aircraft select the airfield by clicking on it and then click where you want them deployed.
To change a unit's current mode right or control click on it and select the desired mode.