That is asking a MAJOR question.
First, learn how to keep your computer secure. The Tutorial below will get you started and provide a good foundation:http://www.bleepingcomputer.com/tutorials/keep-your-computer-safe-online/
Second, use the HELP files provided by the applications and operating system you are using. Taking time to read these can really save you both time and grief.
Third, some "how-do-I-do-this" mini-guides can be found here:http://www.bleepingcomputer.com/forums/f/92/mini-guides-and-how-tos-simple-answers-to-common-questions/
Fourth, don't hesitate to post your questions, even if you think they are very elementary, here on the appropriate forum; all of us here began knowing next to nothing about computers and learned bit by bit, so we are more than willing to answer in simple (well, simple for computers) language.