John,
I just type a heading for the x values in a suitable column and a
heading for the y values in the next column to the right.
Type in all the x values in the cells below the x value heading and
similarly for the y values.
Then select this block of cells then click on the Chart Wizard. Work
your way through all of the steps to achieve the desired chart. I
strongly recommend using the X-Y scatter chart. I never use Excel's
line chart. If your x values go 1,2,3,5,6 instead of 1,2,3,4,5,6 it
will put the 5 right next to the 3 instead of throwing in a 4 ie the
axis is not evenly subdivided.
Hope this helps
Ken Johnson