With over 60,000 viruses around, we recommend that you do NOT use the Internet for e-mail or browsing (browsing is when you are using those www.whatever.com things) without some form of anti-virus protection, that is kept up-to-date.
The most common way to do this is to have an anti-virus program on your computer, and keep it up-to-date.
Some Internet Service Providers (the company that you buy your Internet service from), now have built in anti-virus software that checks for viruses in each of your e-mail messages, before you receive them. Some Internet Providers include this in their service automatically, some charge an extra fee for it, and some don't have it yet.
My Internet Provider has a built in anti-virus program, but I still use an anti-virus program on my computer, as a double check, and so I can periodically check my whole computer for viruses. But for beginners, having an Internet Provider that checks each e-mail for viruses, is a great way to reduce the chances of getting a virus.
For an anti-virus program, I prefer the Norton Anti-Virus program, because it is easy for beginners to update. McAfee is also very popular, and there are other programs. If you are not sure about this, talk further with your computer supplier.