I have a linear programing problem but I am not sure where to start.

An artist is creating a mosaic that cannot be larger than the space allotted which is 4 ft tall and 6 ft wide. The mosaic must be at least 3 ft tall and 5 ft wide. The tiles come in two sizes: Smaller tiles are 4 in tall and 4 in wide, the larger are 6 in tall and 12 in wide. If the small tiles cost 3.50 and the larger tiles cost 4.50 each, how many of each should be used to minimize the cost? What is the minimum cost?

It says the solution must include: Objective function, constraints (inequalities) and then a graph of the constraints.

What do I need to set up or is there anything I can read up on, because when I was reading up on constraints and stuff it still didn't really make sense.