A homozygous dominant genotype is composed of two dominant alleles like for example AA
Where A is a dominant trait
Before anything else remember first that a genotype is a genetic constitution of an organism for a certain character. Alleles are alternative forms of a gene. Example:
For the character of being albino, the allele “A” refers to being normal while “a” refers to being albino. The genotype AA and Aa gives a person normal skin and not albino. Dominant traits are usually assigned a capital letter.