Everybody has a story to tell of how their grandma would stick a piece of rose stem into the ground and then place a Mason Jar over the stem to make it grow. There are tales of how the early American settlers of the 1800's traveled to the far reaches of the wild west in covered wagons, with grandma bringing along "starts" of her favorite roses from back home. Perhaps the treasures of these "monsters on wooden wheels" were raided, and they discovered the Yellow Rose of Texas hiding under the bonnets of the women. Or maybe the settlers used their precious "starts" to barter for provisions along the endless dusty trails.
The Baggie Method: This was the first method I ever tried. Here you fill 2-inch plastic pots with potting soil, insert the rose stem halfway inside the pot, then put the pots into a one-gallon plastic zip-lock bag. You can get four 2-inch pots into each gallon bag. I didn't like this method because it caused many of the cuttings to rot since the bags tended to fold over and therefore prevented the air from circulating. The success rate of this method is not very good. It may be helpful to place a couple of small sticks inside the bag to help keep it upright and full of air.
Northern gardeners need to know exactly what zone a rose is hardy to. Southern gardeners must also watch to see what zones are recommended for each particular variety, as some roses perform very poorly in hot and/or humid weather. Read the catalogs carefully and, if possible, purchase your roses from a local or regional grower. They will be able to advise you from experience about how a particular variety will perform in your area.
Black Spot: Rose plant leaves with black spots that eventually turn yellow have black spot. This is often caused by water splashing on leaves, especially in rainy weather. Leaves may require a protective fungicide coating, which would start in the summer before leaf spots started until first frost. Thoroughly clean up debris in the fall, and prune out all diseased canes.