For HTML 4.01, you can indicate the character encoding in the head of your page using the following meta tag:
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
ISO-8859-1 (commonly called Latin 1) is the default characters set for HTTP .1.1, and indicates a set of common English characters. Generally this is the most common character set indicated in web pages, and is likely to be the one you will use.
Creating valid HTML is one of the most important steps you can take when designing accessible websites. If you do not provide the appropriate character encoding this could lead to characters in your page not displaying correctly, which of course will have an impact on the accessibility of your content.