I’m very confuse please help! The recipe sways nothing about starting with a cooked ham so i bought a raw pork shoulder butt.

Whether or not you need to buy a proper cured ham butt or you cook the pork roast you have depends on you- and if you want this specific recipe to turn out as it is designed. If you are determined to have this recipe, as written- then yes, you'd need a proper ham. If you are not hung up on serving a cured bit of meat, then you can certainly bake your cut and have a really tasty bit of pork roast. You would need to bump the temp up to about 325, but still roast at 20 minutes per pound, until it hits 145F on the thermometer. You could still use the rub and glaze the recipe gives, and it will be right tasty- just won't have the smoky cured flavor of a ham. Not bad, just different. For the best flavor, if you can season your roast and let it sit overnight before roasting, it will be even tastier. For future reference, ham is kind of a confusing term, as is "butt". The rear legs of a pig are what are generally used for making proper cured hams. "Butt" refers to the position of the cut on the leg- you have butt and shank ends. The shank used to have a foot attached, the butt end is the top where you had either the hip or shoulder. It's the "butt end" of the leg, as opposed to the shank, or foot end. On the odd occasion you will find what is sold as a "fresh ham" which is a cut from the rear leg which has not been cured. It's not actually a ham as most folks use the term, it's a potential ham. Anyway it's your call what you want to do. Either way can be yummy in it's own right.