If you right click on a legend, you can use the Format Legend option to then access the various things you may want to change.
Excel 2007:Click on chart.Right-click on ledgend and select Format Legend.In Legend Options, slect the position for the legend (top, bottom, left, right, or top right).Close Format Legend window.
You do not do so directly, since it is part of the chart. You can move it to various locations within the chart box. If you want to display a legend outside the chart box, you can delete the legend from the chart box and type in anything you want into cells near where you position the chart. Be aware that if you delete the legend from the chart box, you no longer will be able to update the legend when the chart changes, unless you draw the contents of the cells holding the legend data from the same location as you get the data for the chart graphic.
If you change the colours for the items on the chart that the legend is showing to have shading, then you the legend will change too. You can also change the background of the legend itself, by right clicking on it and select the Format Legend option and then the Fill option.
If you click on a chart legend you can drag it to wherever you want around or on the chart.
A bar chart.
Legend
The legend is normally positioned to the right of the chart. You can move it to wherever you want though.
Just about every element can be modified on the chart (size, color, source, legend, title, etc.). According to my Spreadsheet Applications book the six chart modicifcations include the following: size, color, font, format, scale, and style.
Chart Tools Format
Use format painter
Use the Insert tab and select from the Charts section.
format for machine loading