The internet is a mixed blessing. It is an astounding resource the uses of which are limited only by your imagination. It can be the source of information and income, but it can also be used for deviant and destructive purposes. Children are the commonest victims of the ambiguous nature of the internet, because they do not have the judgment to know what's good for them and what is not, and to avoid what is not appropriate.
The internet is largely an unpoliced and unmediated place where under the cover of anonymity people can upload or download things that they wouldn't admit to using in a more intimate situation. Online pornography has become such a roaring business partly because of this incognito appeal. How do you prevent your child from getting access to these materials, which are available freely on the information superhighway?
You can protect them with the use of software that can be configured to block sites and materials which do not conform with your moral standards.
First, consider using a pop-up blocker. A large amount of pornographic material is disseminated in the form of unwanted windows that pop up in front of the legitimate page you're trying to read. The Service Pack 2 for Microsoft Windows XP© adds this capability to the default Windows browser, Internet Explorer©. If you don't have SP2 yet, it's about time you updated your system.
Alternatively, you can use the freely downloadable Firefox browser that most people agree is much superior to Internet Explorer in all respects, as also in the pop-up blocking ability. There are also a number of extensions that you can add to it to enhance its capabilities.
Often your child may receive e-mails which contain links to pornographic websites. You can teach your e-mail program to identify these as unwanted mail (also known as spam), so that they can be deleted even before they reach your child's inbox. There are many free e-mail programs, and one of the best with these identifying ability built-in is known as Thunderbird. This uses a state of the art technology known as spam-assassin to block unwanted content.
It is often very useful to configure your internet connection so that it accesses the web not directly but through a proxy. You can then configure the proxy software to block traffic to or from a list of websites that you can edit. Most proxies available for the windows platforms are commercial products, and some of them are quite good.
If you want a non-commercial yet top-class solution, you may want to look at squid, which unfortunately runs only on Linux, the new rival to Windows. If you have an old spare computer at home that you're thinking of putting on the garage sale, ask a techie friend to install Linux on it and configure squid, so that it can act as the gateway through which your Windows machines connect to the internet.
Also, use the inherent firewalling capabilities of Linux to block certain types or sources of traffic. Windows too has firewall solutions, but they are generally less configurable and more restrictive. For one of the better offerings, try ZoneAlarm. You can download a demo version from here.
Although you may not be technologically sound, the safety of your child requires you to take some interest and make an effort. If you cannot do it yourself, ask a friend who can, or pay a support guy who will do it for money.