How can I rewrite URLs on WordPress?
For example, I have a URL like
sitename.com/?page=<numbers>&id=<numbers> and I want to rewrite it as
sitename.com/page/id/<other info>. How can I do that? I don't understand the rules!
Your best bet for an easy solution is to actually use the "Custom Structure" option in your WordPress admin under Settings > Permalinks.
If you're looking for even more customization and manual control, it's actually a pretty complex topic involving editing your .htaccess file. This great two part tutorial by Stephan Harris covers this topic very well. (Better than I ever could here on SO).