Can you explain how genetic diagrams of inheritance work?

Explanation of keys words first; a gene is a section of DNA that codes for a particular characteristic such as eye colour. An allele is a version of a gene (e.g. an allele for the eye colour gene could code for blue eyes or brown eyes), and they can be either dominant or recessive. A gamete is a sex cell (a male gamete is a sperm cell and a female gamete is an egg cell). The purpose of genetic diagrams of inheritance are to help understand the possible outcomes when parents produce offspring; a useful application of genetic diagrams might be to determine the likelihood of an individual inheriting a genetic disease such as Cystic Fibrosis.  I will have genetic diagrams to explain drawn on paper