Explain throughly please, I'm having a hard time understanding FSM's.

The UNCC IEEE student chapter is co-sponsoring a tea vending machine with a heavily subsidized price of 15 cents a cup. Design a Mealy FSM for the vending machine assuming the students can load nickels (input N) and dimes (input D), only one coin at a time. If the user tries to enter two coins at the same time, the vending machine would not allow it, i.e. it will stay in the same state. If the user pays more than 15 cents, no change is dispensed (i.e. if the user enters a D when the running sum is 10 cents, the FSM will count the total as 15 cents and dispense no change). The vending machine will dispense the product (output P will be pulled High) as soon as there is enough money entered and then reset unconditionally. Use the following format for the inputs: ND. Use active-high logic to indicate an input or output is active. Show the state transition diagram, state assignment table, state transition table, next-state equations, and output equations. Use K-maps to extract the most simplified equations. Design a Moore FSM that will detect the sequence "1001" with overlap (i.e. the bit stream "1001001" will be detected as two instances of the sequence). The output Y should be a '1' when a sequence has been detected. Use D flip-flops for state memory and set the next-state and outputs of unused states to the Reset state and '0', respectively. Show the state transition diagram, state assignment table, state transition table, next-state equations, and output equations. Use K-maps to extract the most simplified equations