It doesn't sound dumb at all - especially if it's something you've never done before.
The procedures are as follows:
For Internet Explorer:
Click "Tools" to open the menu
Click "Internet Options"
Under "Temporary Internet files", click "delete files"
Check "delete all offline content", click "ok"
Close it and you're done!
For Netscape and Mozilla:
Open menu under "Edit"
Click "Preferences"
Double click "Advanced" to show more listings
Click "Cache"
Click "Clear Cache", then "OK".