Electronic mail is a great way to send a quick message to people as opposed to "snail mail" which is sending a letter through the postal service.
Some e-mail will allow you to see messages in what is called html (hypertext markup language) so you can click on links, see pictures and view it as you would a web page. Others will not. So if you get an e-mail from a newsletter or e-zine to which you subscribed and get something that looks like a bunch of gibberish code, then you cannot get html e-mail and need to contact the newsletter asking them if there is another option since your e-mail client cannot process html. They may just direct you to a web site version of the newsletter, give you one in plain text, or simply unsubscribe you.
E-mail also allows you to send and receive files in the form of an attachment. Some services use a paperclip and others use a symbol of a floppy disk to let you know there is an attachment to your e-mail. If you open any attachment, BEWARE!! Do not open an attachment from someone you don't know. Proceed with caution if the attachment is from someone you know.
The general rule is unless you are expecting a file from someone, don't open it and if you do, make sure you have an Anti-virus program running.
If you want to be on the safe side, if a friend sends you an e-mail with an attachment unannounced, send them a quick e-mail asking if they sent it to you. There are some viruses that copy down address books from your friend's computer and can send you the virus if you open it thinking your friend sent it.
Sometimes you may have requested a file be sent to you from a business associates or contact or from an offer online by a reputable source. They are usually safe, but keep the Anti-Virus scan running just in case.
Your computer will not become infected simply by opening an e-mail, although the contents inside may make YOU sick. Your computer will only become infected if you open the attachment to the e-mail if the attachment contains the virus, worm or whatever bomb it may have inside.
Many newbies are tempted by the "free" offers and contests on the various sites then within weeks their e-mails are flooded with many business propositions, advertising and other undesired e-mails. They will find themselves on many mailing lists for such things. Sometimes even porn invitations will cross your inbox. These are more annoying and prevalent than viruses and worms. They are also harder to control once you get caught in the trap. See the section on "Spam" for tips on how to cope.
E-mail is a great tool, so don't let phobias spoil your fun. Turn on filters to scan through the mail you want to read and delete the rest. Don't be afraid of opening e-mail, just use caution when opening attachments to e-mails.
And for goodness sakes, please - don't fall in the trap of forwarding garbage! It makes you look silly. See "Internet Hoaxes".