Engineer
Sentry Gun 1
Det Pack
This is what the sentry gun first looks like when you build it. It is weak and shoots slowly. You should be able to take out weak units such as Scouts, Snipers, and Engineers. You should upgrade quickly.
Sentry Gun 2This is what your sentry gun will look like after the first upgrade. It now has a bigger gun and is able to shoot faster. With this you should be able to kill medium armored enemies. You can still upgrade your sentry gun one more time.
Sentry Gun 3This is what your sentry gun will look like after your final upgrade. This is a much more powerful weapon. It now has to barrels and a rocket launcher. If the enemy survives the shots, then the rocket will finish him off. Now you are able to kill even the Heavy Weapons Guy.
DispenserThis is not really a weapon. It should be placed where your teammates can get to it. When they walk up to it a menu will pop up. It will ask if they want armor or ammo. This is the alternative to going to the resupply room.
Demoman
This is usually used for blowing up fences and weak barriers. In such maps as Rock2 and Well, the det pack can be used to open other ways into the enemy base. You can also use this as a weapon. Set it and run like hell. The blast radius that is seen is rather small, but the shock wave it creates will blow apart anyone from a fair distance. The only protection against it is a barrier. When you hear a sound like something is starting, that’s the det pack getting ready to explode. There are three settings, 5,20, and 50 seconds. Go into the console and type bind x +det5 (x being the desired key). Then you can do +det20 and +det50.