Help with encryption

Howdy all - I have RTFM and STFW and I still can't get encryption to work. What I finally ended up with from the PHP documentation is long, unwieldy, confusing, and doesn't work. I give up. I threw my big mess away and would like to start from scratch. Could anyone point me to a web page or other documentation that shows a SIMPLE example of encryption? I need two-way encryption & decryption, not a one-way hash. I'll be using this to obfuscate get parameters. Any pointers appreciated. Thanks all, - Brian