Maxum,
I do not think I can do as well as CLA has, but to help share the load, I will give your low and high pressure question a shot.
Low Pressure
When there is a core of warm air, it forms a lift in the atmosphere. That lift is creates a slight vacuum at the center, hence a low pressure area. Near the center, the warm air is lifting and cooler air circulates down away from the low center to replace the air that lifted. In the northern hemisphere, this lifting and cool air recovery spins anti-clockwise or counter-clockwise. The more lift, the deeper the low pressure and the more the spin. During this process, the warm air reaches a point where it can no longer hold all it's moisture and as a result, precipitation begins.
High Pressure
The complete opposite of low pressure. With a high pressure area, we have a cold center with sinking air. That sinking air is like air coming from a leaf blower. This air flow applies a higher pressure at the surface. The cold air is dry relative to the air around it. The more this cold air sinks to the surface, the higher the pressure. Because of the dry air, high pressure areas are associated with clear weather.
There are many web sites that give good, free basic weather information. He are a few of them.
http://www.usatoday.com/weather/wlowpres.htm
http://www.bbc.co.uk/weather/feature...pressure.shtml
http://www.stormsurf.com/page2/tutor...erbasics.shtml
Good luck and thanks for asking!
R2B