According to LoveToKnow, you can breed your Rottweiler by natural mating methods or by artificial insemination. If you have access to a quality stud for your bitch, you can use natural mating. If not, you can try artificial insemination.
Most dogs can breed naturally, so this is the method most commonly used by breeders. However, you can also ask your vet about artificial insemination, which allows you to obtain quality sperm from dogs around the world. This method is great for breeders who want to produce a higher quality dog than they would be able to with dogs in their immediate area.