Sounds are as important as graphics in a game. People might not want to watch a silent battle being waged or play guitar hero with no music. Game programmers often have others help them with their sounds but it can be done by anyone really. You just need a few things available.
1. A microphone 2. A computer 3. A free or paid for sound editor/beat mixer
The simplicity of a sound might surprise you. You can record sounds like a cell phone tapping your desk or a rock hitting the ground and use it as a click noise. This was done with I.N.D.E.N.T and actually makes a nice clean effect after it was smoothed out using a sound editor.
Along with these ideas, you can often take a High-DB resistant Microphone and record real life sounds like gun shots or perhaps the roar of a car engine starting. You simply need to get an idea and record it. ___________________________________________________________________________________________________ Producing music is a whole new deal. Many professional mixers will say you need a keyboard and a kick set to produce clean sounding songs. This is true to a point, but many mixers have built in keyboards that can be used. As I have no experience in beat mixing, I suggest you find a tutorial online and read through it.