Integration of Search, Log-in

Oh, and one more question: If I'm modifying the header template (main.tpl) and using my own code - how do I make it display  'login' and 'register' only if the user is not logged in? I know there's PHP code to do it, but can't seem to find much info

i've been trying to integrate punBB stuff on to other pages on my website. the forum is at /discussion/, and my PUN_ROOT is set to './'

if i go in to the /my/ directory, and try and link back by putting in

define('PUN_ROOT', './discussion/');
require PUN_ROOT.'include/common.php';

it doesn't work, despite the "integration docs" saying this. if i change the /discussion/index.php (the punbb homepage) to './discussion/' from './', it just tanks, giving the following response:

response from /my/

Warning: require(./discussion/include/common.php) [function.require]: failed to open stream: No such file or directory in /home/main/public_html/my/index.php on line 6

Fatal error: require() [function.require]: Failed opening required './discussion/include/common.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/main/public_html/my/index.php on line 6

response from /discussions/ with PUN_ROOT set other than './'

Warning: require(./discussion/include/common.php) [function.require]: failed to open stream: No such file or directory in /home/main/public_html/discussion/index.php on line 27

Fatal error: require() [function.require]: Failed opening required './discussion/include/common.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/main/public_html/discussion/index.php on line 27

this is confusing the hell out of me, i can't grasp how PUN_ROOT is expected to work, and why it's not. it seems like it should be an absolute from the / of the site, but it doesn't function this way. and something's locked so that anything outside of /discussion/ can't talk to punBB.

all i want to do is have a line on each page (in all the different directories, such as /my/, /watch/, /create/, and so on), that says 'you're logged in', or 'you aren't logged in'. with a few extra links of course... plus i installed and spent 22hrs customising punBB so i could use the authentication and base user management for the whole site! eep.

i hope someone can help clear all this up for moose! thanks in advance