Is there a way to make a text note when someone comes into the forum?

I would like to be able to make a text comment on my main.php. What I am doing is I shoot sports photographs and I give people a card so they can come and download them if they like them. I also put a Paypal link if they want to donate for the pics. I got the link (I have no idea how to center it so it looks crappy, but it is there), but now I want to put a note somewhere to remind people that donating isn't a really bad idea. I know little to nothing about HTML and even less about php. I built most of my site except the flash portion, but it was all trial and error. HTML is pretty logical. I can't make heads or tails of this PHP stuff.

Gallery version 2.3
PHP version (e.g. 5.1.6):
PHPInfo Link www.brianjeremiah.com/discgolf/phpinfo.php.txt
Webserver
Database
Activated toolkits
Operating system
Browser Chrome

Last Run Details:

Gallery URL = http://www.brianjeremiah.com/discgolf/main.php
Gallery version = 2.3 core 1.3.0
API = Core 7.54, Module 3.9, Theme 2.6, Embed 1.5
PHP version = 5.2.8 cgi-fcgi
Webserver = Apache
Database = mysql 5.0.67.d7-ourdelta-log, lock.system=flock
Toolkits = ArchiveUpload, Exif, Gd
Acceleration = full/900, partial/900
Operating system = Linux p3nlh100.shr.prod.phx3.secureserver.net 2.6.18-92.1.10.el5PAE #1 SMP Tue Aug 5 08:14:05 EDT 2008 i686
Default theme = matrix
gettext = enabled
Locale = en_US
Browser = Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/530.5 (KHTML, like Gecko) Chrome/2.0.172.31 Safari/530.5
Rows in GalleryAccessMap table = 12
Rows in GalleryAccessSubscriberMap table = 45
Rows in GalleryUser table = 2
Rows in GalleryItem table = 45
Rows in GalleryAlbumItem table = 2
Rows in GalleryCacheMap table = 6

www.brianjeremiah.com/discgolf is the web address.