Parsley is native to the central Mediterranean region, though it has naturalized in other places and is grown widely as an herb and a vegetable. It is a biennial, growing only leaves the first year. You'll get some new leaves the next spring, but as soon as the flower stalk starts, the leaves will have a more bitter taste. If you want to save seed, let the blooms form, but if not, you just need to compost last year's plants and get some new ones started. The plants will die after making seed, so no point taking up garden space with them if you aren't trying to make your own seed. I start mine ahead of time in the greenhouse and set them out in spring. The seed can be slow to germinate, so give yourself plenty of time. Parsley is one of those things with a taproot that sometimes don't transplant well, so you might try growing it in peat pots, or some of the other types of pots now on the market that can be planted directly in the ground without disturbing the roots of the plants.
Parsley grows best in moist but well-drained soil in full sun. One or two plants will be plenty for most people since you won't be harvesting the whole plant, but rather just picking a stem as needed. I grow mine in what you might call a raised herb bed. In reality it is a large black nursery pot, not sure of the size, but a really big one. I did this to keep the rabbits away from it and it has worked well. I usually put a plant of sage in there too, along with the resident clump of chives that has been there since I started the pot over 10 years ago. The only other pest you might have trouble with are caterpillars from Swallowtail Butterflies. The caterpillars are green and yellow striped with black dots. They will feed on your parsley for about 2 weeks before heading off to turn into butterflies.
Parsley is one of the easiest things to put up to use over the winter. I just pick it, rinse it, dry it and put in in zip loc freezer bags. I squish the air out of the bags to keep freezer burn away, and usually have plenty of parsley to last the winter for cooking. It doesn't take up much room in the freezer and is much tastier and greener than when I've tried drying it in the food dehydrator. Frozen parsley is not as crisp as the fresh (actually not crisp at all) but the flavor is every bit as good.