2001 Dodge Caravan

Engine Mechanical problem
2001 Dodge Caravan 6 cyl Front Wheel Drive Automatic

THE ENGINE LIGHT IS ON TOOK IT TO A LOCAL AUTO ZONE THEY PUT IT ON A COMPUTER TO READ THE CODE, IT CAME UP WITH P0456 SAYS LEAK IN THE EVAP SYSTEM. PROABLE CAUSE #1- DEFECTIVE, LOOSE OR MISSING FUEL CAP. I CHECKED THIS IT LOOKS GOOD. #2- EVAP CANISTER BROKE, HOSE CRACKED OR NOT CONNECTED. WHERE WOULD I FINE THIS? #3- PURGE OR VENT SOLENOID DEFECTIVE. WHERE WOULD I FINE THIS? #4- VACUUM LEAK AT ENGINE. ANY EASY WAY TO FINE THIS?