Charcoal, at least the briquette-shaped consumer kind, doesn't ignite easily. You need to use an accelerant to help it along. Commercial lighter fluid meant for grilling, rubbing alcohol, or liquors greater than 150 proof (75%) all work equally well. Kindling, like wood shavings or newspaper, helps too; it lights up quickly even without an accelerant, spreading the flames to the charcoal (which should already be saturated with the accelerant).
One word of warning though: DO NOT squirt lighter fluid directly onto an existing fire. Pour the accelerant onto the charcoals first, then use a match. Otherwise, the flame could travel up the fluid stream and into the can, thus injuring your hand without putting you on the bus. If you must add lighter fluid to an existing fire, pour it into a paper cup, and shake it out it in small bursts onto the fire from the cup, then throw the cup into the fire.