In all versions of Mac OS X, there is a very handy tool called Software Update, which checks your computer and determines if there are any updates available for you to download and install. These range from updates to your Quicktime player to overall security updates for your entire operating system. Also included are updates to your Safari browser, which can be crucial to your browsing safety. Sometimes, when a security flaw within the Safari application is discovered, Apple will release a new version of the browser to correct it, and this can usually be downloaded and installed for you directly from the Software Update application. It is important that you check for updates often and install those that are crucial for security, such as these browser updates. Keep in mind that browser updates are not only for security purposes, as they often feature enhanced functionality. However, from a safety perspective, it is always important to keep your browser updated to the latest version.
First, make sure that you are connected to the Internet. Next, to manually launch the Software Update application, click the Apple menu (located on the upper left hand side of your screen) and select "Software Update...".