If you plan to use a scale, I would recommend a digital scale. It is more accurate than a spring-loaded scale and easier to use. One of the key features it should have is a tare feature, which I will describe below. In terms of accuracy, the better scales can weigh within 0.05 ounces (the U.S. standard) or 1 gram (the metric standard). In most cases you won't need that degree of accuracy but there are now a fair number of scales on the market that can deliver that accuracy. I would look for a scale that can handle grams (and kilograms) in addition to ounces (and pounds) since there are quite a few recipes that are based on the metric system. You will perhaps want to have a scale that can weigh at least four pounds and preferably more if you plan to make large batches of dough or if you intend to use the scale for other large batch baking applications. Many digital scales also have a time-out feature that turns the scale off after a specified period of non-use. This is to preserve the battery.
I have seen scales meeting all or most of the above features and criteria starting at around $25 and running to over $50. If you do a search on the forum for scales, or look under the equipment boards, you should find recommendations and examples of scales that you might want to consider.
For the most part, the scale will be used primarily for weighing flour and water. They constitute the "heavy" ingredients used to make dough and make up the bulk of the weight of a finished dough. However, the scale can also be used to weigh large amounts of oil and cornmeal and such. In most cases, the scale won't be able to accurately and precisely weigh out small amounts of yeast, salt and sugar. For these ingredients, you will use volumes.
In terms of how a scale is used to weigh ingredients, I can only speak for my scale. It is a simple scale with only a single button. To turn on my scale, I push that button. A digital scale just above the button will register zeros when I do that. To weigh a quantity of, say, flour, I put a container that is to hold the flour on the scale platform and press the button again. This is what is called a "tare" function and what it does is to effectively "zero" out the weight of the container. This "zeroing" out feature will be reflected by zeros appearing again on the display. When flour is added to the container on the scale platform, the weight of the flour will appear on the display as you add the flour. You will usually have to tweak the amount of flour in the container to get the precise amount of flour you want. I do the fine tuning by using a teaspoon or tablespoon. The display will register either ounces/lbs. or grams/kilograms depending on which system you set the scale to use. On my scale, there is a switch under the scale that allows you to select either the U.S. standard system or the metric system.
Once the desired quantity of the flour is in the container, you can set the container aside. I might add that with some scales, the container is a specially designed container that comes with the scale. With some models, it is also possible to weigh ingredients on the scale platform without the need of a separate container. My unit did not come with its own container, and I almost always use a container rather than weighing directly on the scale platform. You can use whatever container you have on hand, although its size should be commensurate with the amount of the flour to be weighed. I should also mention that it is possible to do successive tare operations, each of which zeros out the weight of all of the ingredients then in the container in preparation for weighing the next ingredient added. This is not a feature I often use, but it can come in handy when needed.
To weigh water, I use a standard glass Pyrex measuring cup. I use the tare feature to zero out the weight of the Pyrex container, and I then add the water (or other liquid) to the container until it gets to the desired weight. Again, you may have to tweak the amount of water to get the precise amount you want. When you reach that point, you can set the Pyrex measuring cup aside and move on to the next step in your pizza dough making. One of the reasons I like using the Pyrex container is that I convert most of my formulations to volumes and using the Pyrex cup allows me to eyeball how much water I have weighed on a volume basis. Any other type of container will also work.
As you can see, the process is quite simple. My unit (a Soehnle Futura) is so simple that the only instructions I got with the unit was a single sheet with only sketches on how to use the unit. My recollection is that there were no written instructions.