How do you change the legend from series to an actual value?

I've created a chart and right now for my legend it says series 1, series 2, series 3 and so on.....I want to change it to an actual word like Kathy, John, Robert and so on.

My x-axis should show the years 2010, 2011, 2012, 2013 but instead it says 1,2,3, and 4. How do I correct this? I have Excel 2007 and I can't click and rename it.

If you don't want to start the chart from scratch, right-click the chart > Select Data

In the right hand side panel, click Edit. Click in the box for Axis label range and then click the cells that have the years.

Select Series1 and click Edit. Click in the "Series name" box and then click the cell that contains the name for the series.
Repeat for the other series.