How do you solve using the BAII Plus calculator?

Solve for ordinary annuity options present value using the BA II Plus Calculator. I've included the answers, but need to know how to work on the calculator.

One payment of $1,200, for each of three years, with an annual discount rate of 4%. $3,330.11

Twelve Payment of $100 each, for each of three years, with an annual discount rate of 4%. $3,387.08

Four payments of $300 each, for each of three years, with an annual discount rate of 4%. $3,376.52

Two payments of $600 each, for each of three years, with an annual discount rate of 4%. $3,360.86