A good compass will be marked with a very detailed and accurate set of degree lines and most will have the North-pointing tip painted red so that it is easy to distinguish from the South-pointing tip. Most, but not all, compasses will also point to magnetic north and it should be remembered that there is a difference between magnetic North and true North.

A large concentration of ore under the surface of the Earth's about a thousand miles away from the North Pole causes the compass needle to deviate from true North and this deviation will become greater as you approach the Pole. Some compasses have mechanisms that allow you to adjust for this and your map will normally indicate the degree of adjustment that is necesary.

For most areas, the difference is minor and you don't really have to worry about it as you're often more concerned with the general direction in which you should be heading, rather than the absolute bearing you should follow. Also, in most cases, you can simply adjust visually by turning the map a bit and not paying too much attention to true North.

Here's one quite simple way to use your compass to find your position. Find a landmark which you can see and that you can locate on the map. Draw a line from that landmark to the point where you think you are on the map. Then, find another landmark which is at least 45 degrees from the first and repeat the process. Where the two lines intersect is a pretty good approximation of your present location.

You can also use a compass to orient yourself by combining what you see on the dial with some basic knowledge. For example, the sun rises in the East and sets in the West so, early in the day, face the sun and you'll be facing (approximately) East. Similarly, face the sun late in the day and you'll be facing West. This is only an approximation of course, but it's a sound starting point.

Once you know the approximate direction you're facing you can then line your compass up and then turn your map so that it is also aligned North/South.

Often, simply knowing the general direction you want to travel is extremely helpful. It is very easy to get disoriented when you are climbing up and down hills and knowing even the approximate direction back to your desired location can help keep you from getting lost.

One final point - whenever you step off the trail, make a note of the direction you are going when you do so and keep track of any twists and turns you make. That way, if you do lose your direction, and can't find the trail again, you'll be able to use your compass to help get you back to where you started.