Answer:
The Punnett square will look like this:
Rw Rw
Rw Rw
Explanation:
In order to have a white flower, both alleles must be recessive. A homozygous red flower must have two dominate alleles.
Well use (w) for white, and (R) for red.
The parent alleles are:
1 - ww
2 - RR
(see picture)