Ok so I'm having difficulty understanding how to Take a regular expression and turn it into a finite state machine..

so heres a problem similar to the one I need to solve..

Say I have a machine that takes £1 coins, dispenses beer(£1) and water(£2)

so the values for a regular expression are;

p = inserting a coin

c = dispense beer

b = dispense water

(Also buttons to dispense cans)

B = beer button

W = water button

and lets say ppWb represents buying water..

REG = (pBc+p(e+p)Wb)* (e is an empty string..)

so how do I derive this into a finite state machine? I can vaguely turn this into a syntax tree, then where do I go from there?

I'd really appreciate some help :?