Renaming the points on my X Axis and the lines in my Legend

[JillyKaren]

I have successfully constructed a multi-line chart from the data on my spreadsheet. The title and the points for the Y axis are correct, and the title for the X Axis is correct, but the points on the X axis are not correctly named and the lines on the chart are incorrectly named in the Legend. I have looked everywhere I can think of in the Help files and in the program itself to locate how to do these things, but no success. Could someone show me, please and thanks in advance.