This is all easily done in the “Analytics Settings” page by clicking “Edit” next to the account you wish to edit, and then creating a Goal in the “Conversion Goals and Funnels” menu. Check out the Google help page on How to Setup Goals and Funnels for more details on how exactly to set them up.

Once Goals are setup, you can run reports to see which of online marketing efforts are paying off.  For example, you can go to the “All Traffic Sources” report, click on “Goal Conversion” and quickly see data on how referall traffic, organic search, or PPC are doing in regards to conversions and revenue per visitor.  To see the total amount brought in my each medium or source, you need to run a Custom Report.  Under “Metrics” in the custom report, choose an appropriate metric such as “Goal 1 Value” or “Total Goal Value”.  Under “Dimensions” choose “Medium” to see the totals for referall, direct, cpc, and organic – choose “Source” if you want to break it down by domain.  Now you have some essential data, and you can save this report and rerun it anytime you want.