Hi, this tutorial will show you how to create a convincing flashlight in HL2. The light will move dynamically with the torch.
Firstly you need to make a convincing flashlight brush, I can't really help you with this, but you can copy mine from the VMF file. Select the torch and create an entity (Ctrl + T), set it to be a Func_Physbox and set the name to flashlight. I haven't changed any other settings, but feel free to experiment.
Once you have made the torch you only need to add the point_spotlight entity to the light end of the torch and make sure it's facing the right way. Go into the properties and set its 'Parent' to flashlight. This makes it so the point_spotlight will stick to the flashlight.
Now load up a map and throw em about