How do I open attachments?
First and foremost you must have an up to date anti-virus program. If you don't have one, get one before opening any attachment or email for that matter.
Attachments can be a mixed bag of surprises. Ordinarily an attachment is simply a file of some sort that somebody wished to share with you. However, under adverse circumstances, an attachment can carry with it a harmful virus that can potentially damage certain files on your computer, if not your computer itself, in the worst cases. It is important to identify the attachments that you're going to open before doing so. Only open an attachment that you are expecting and only when the sender tells you that there is an attachment and I don't mean 'click on the attached file'. It's to impersonal. It should be more like 'the picture I told you about is attached'. It's more personal and the chances are better that it is from your friend.
When you receive an email that has an attachment you will see a paper clip to the left of the header. See below. Open the message by double clicking on it.

When you open the message you should see, as shown below, an attachment listed under the subject. Double click on it.

You should now see the window below. Click on open and you should be able to view the attachment.

The above is based on Outlook Express, but the techniques should be very similar in most email programs.