I am absolutely new to Excel and am having trouble interpreting the Help screens. I am learning by trial-and-error and need the most rudimentary help. For example:

Given a worksheet with 5 numbers in Col. A and 5 numbers in Col. B ... how do I print in Col. C1 through C5
a1*b1, a2*b2, a3*b3, a4*b4, a5*b5?

1) In what box(es) do I enter the formula? -- Do I have to insert an*bn in all 5 cells in Col.C?

2) After I enter the formula, what key do I click to start the operation?

Thanks.