Roller Skating takes practice, but after a while, it can come as naturally to some people as walking. It is simply a matter of getting used to the feeling of having wheels on your feet.
Start slow: If you are just getting comfortable on skates, or just learning how to roll, then starting slower may actually help you learn quicker. Once you get the feel for balancing with wheels on your feet, you become much more comfortable and relaxed. An understanding of your personal sense of balance will provide a much more solid foundation from which you can learn on. From there working your way up will feel much more natural.