Ok so to understand how to make a punnet square you need to know whether they are heterozygous, or homozygous, and know what the phenotype and genotype are. Now to find this answer to 2 and 3 you need to put on top and to the sides of the squares, Tt, and Tt for the top and side of 2. Now phenotype means physical appearances in the organism and genotypes are well, in the gene and how you were made to look like you. Knowing this, the phenotype for 2 and 3 would be the height of the pea plant and the genotype for 2 and 3 would be the traits they had so say Tt or TT something like that. Now to fill in the punnet square you need to cross the boxes and put in the traits there so the boxes from left to right for question two is TT, Tt, Tt, and tt. For question 3 left to right is, TT, TT, TT, Tt. Hope this helped, feel free to ask questions if you have them!