design verilog code of 4 bits alu and after that i can use it to implement 32 bit alu

i am a master student and ihave to design alu for 32 bits including the 4 main arithmetic operation (addition , subtraction, multilication ,divisin) can one help me i am a master student and ihave to design alu for 32 bits including the 4 main arithmetic operation (addition , subtraction, multilication ,divisin