You can insert a graph by selecting Insert Menu < Chart.
A new window opens showing a dummy spreadsheet, a graph based on that
dummy data, and chart menu and toolbar options become activated.
Experiment with the data sheet by clicking on a cell and typing your
own data, to understand the effect of the data changes on the chart.
After you've finished entering data, exit the work window by clicking
anywhere outside the chart or the data sheet. The data sheet will
disappear.
If you need to make any revisions to the chart, double-click the
chart and the data sheet will appear again.
PowerPoint defaults to bar graph. You can select another type of
chart through the Chart menu < Chart Type.
Note: the Chart and Data menus are active only when
the chart is selected and the data sheet window is open. Double-click
on the chart to open the data sheet and activate the chart menu.
You can change the chart options, such as titles, axes, gridlines,
etc., by selecting Chart menu < Chart Options.
You can also change the chart area colors and fill effects by clicking
on the outer or inner chart area respectively:
If you click in the middle of a bar/column/line, a little square
handle will appear to let you know that you have selected a data series:
Right click on the square handle or select Format < Selected
Data Series to change colors or to calculate error
bars.
You may also choose to represent some data series as bars and others
as lines on the same chart. Right click on the square handle or select
Chart < Chart Options:
Always remember that you need to select the appropriate
graph component in order for the respective command to be active. For
example, if the graph area is selected, the command for error bars will
not be visible. You may not be able to select the right thing at first.
Frustrating though this may be, have patience and keep trying. Eventually
you will get a handle on it.