NPV discounts future cash flows to today at your required rate of return and adds them up. IRR is the rate that makes that total exactly zero. A project with a positive NPV, or an IRR above your rate, earns more than you require.
Excel's NPV has one trap that catches almost everyone: it treats the first value in the range as one period away. If the range starts with the year 0 investment, Excel discounts it by a year it should not. Keep year 0 out of the range and add it on its own:
=B6+NPV(rate, C6:G6)
IRR works the other way. It needs the whole series, year 0 included, and at least one negative and one positive value: =IRR(B6:G6).
Both functions assume the cash flows are evenly spaced, one period apart. When they fall on real calendar dates, use XNPV and XIRR, in the next lesson.