Computer management opens the same management console as right clicking on my computer, click manage. From there you can look at various things and/or change settings, such as event viewer, services, indexing, device manager, performance logs (if performance logging is active),  disk management, defrag, etc. Many of these can also be reached in other ways. For example you can just look at event viewer or services by opening their respective applet in administrative tools, or by typing the appriate command in start/run box. Or you can reach Device manager by right click my computer, properties, hardware tab, device manager, etc.

 

Event viewer logs the events recorded by processes and apps that are running. Useful for diagnosing crashes or other malfunctions.

Services is where you can control what services are started automatically, manually or are disabled (there are guides that you can find by googling, don't change things unless you know what you are doing).

Performance is a neat app to use if you want to check out in detail how various things are performing (more detailed than in task manager, but similar)

Datasources, Component services, .NET framework, I would not worry about, unless you are involved in setting up and querying databases, or are into application development. But read the help files if you are interested.