Here are instructions for some common browsers:

Internet Explorer

Go to Tools in the top menu bar. Choose Internet Options. Click on Delete Cookies, and Delete Files buttons. (If it has been a while since you did this you will likely have a long wait while it clears the temporary files.) After it is finished deleting the files click on the Settings button (next to the Delete Files button). Set your browser to Check for a Newer Version of Stored Pages "Every Visit to the Page". Then click on View Files at the bottom of the window. If you have any files left in this window please select them and delete as well. Close the window. Click OK to close the Settings window, and OK to close the Internet Options window. Restart your computer, and try to access the website again.

Mozilla Firefox

Click on the Tools menu at the top. Choose Options >> Privacy. Clear Cookies and Cache. Now restart your computer and try to access the website again.

Netscape

Click on the Edit menu >> Preferences . Under the Privacy & Security category choose Cookies. Click on the Manage Stored Cookies button, and then Remove All Cookies. Close the window using the Close button. Now look at the Category list again and choose Advanced >> Cache. On the Cache page click on the Clear Cache button. Click on OK to save the changes. Now restart your computer and try the website again.

For Microsofts article on clearing your cache see the link below:
http://www.microsoft.com/windows/ie/using/howto/customizing/clearcache.mspx