Hello, if any one knows how to fill in a punnet square please help me

You can fill the sides with any allele.
After that the first box will be the dominant allele than the recessive allele, the box below that will be the dominant allele and the recessive allele. Dom being capitol and recessive being lowercase, the box on the top right will be dominant allele and recessive and bottom dominant and recessive. It’s all based on the allele of that row and column.

Write the letters then go down then across.

The offspring will be blood type aa, bb, ab and oo or i