I want to breed West German Showline, and my breeder is going to help me.
Who is your breeder? Hopefully, they are ethical and responsible, and their dogs are doing more than just breeding. You absolutely must have a mentor, and a good mentor is gold. However, a mediocre mentor can perpetuate mediocre dogs and ideas, and will suck the life right out of the breed.
I thought I wanted to be a breeder when I was 17, too! Then I got into veterinary medicine when I was about 20, volunteered at the local shelter, and started learning how to groom. Within a couple of years, I could no longer imagine being a breeder!
I suggest you get some background in caring for animals before you go into breeding. Study to be a vet tech, or get a job at a local vet clinic, kennel, or shelter. Get some animal knowledge and experience under your belt FIRST. I imagine you are still living with your parents, and are still in high school. Are you planning to go to college, or get a job right out of high school? Where are you going to live? You must make sure your house and your neighbors are amenable to a dog breeding operation. You must make certain you have a good, reliable source of income because breeding is very expensive when done the right way--remember, you will NOT make money breeding. Any profit you might see from puppy sales will be eaten up by caring for your dogs, medical emergencies, x-rays, testing, trialing, showing.
DO NOT get an animal you intend to breed until you are really ready and able, and have a specific goal in mind. You want to raise German showlines, AND police dogs? With all due respect to the SL breeders, these are two different goals. Not saying it can't be done, but top show lines do not often go on to become police k9s. They generally are looking for working lines.
You also have to train and title your dogs in SchH before you can breed if you are doing it the German way. Join a SchH club now, and observe. When you get your first brood bitch, she will be your foundation, so you must have a very special one. What if she doesn't make the cut, not able to get that SchH title or conformation rating you want? What will you do with her?
So you see, breeding is quite fraught. If after reading all this, you are still excited to learn and watch, and then do all the things you need to do, then I'd say you are on the right track to becoming a future breeder!