A gene is a trait that you have but a allele is what of that trait?

Trait is a phenotypic character we are looking at(for e.g. height, skin colour, eye color, etc.)

Gene is a segment of DNA that controls the expression of a particular trait i.e. it codes for the proteins required for the expression of that character. (for e.g. gene for height, gene for skin color, etc.)

Alleles are different alternative forms of a gene. (for e.g. gene for height can have 2 alleles- tall and dwarf)

the offspring would all be white. if the parents are both white flowers then they have the genotype rr, which when crossed results in an all white punnet square.