Router log in page

Hi all
Just wondering what is the best way to edit the router board log in page? I have edited it in an html editor add a text editor both. Every time I have killed the log on link. I was just adding some txt below the log in window to let visitors know I am running a private Air-stream access point with a mail to link to me and a link to www.air-stream.org.au. The page works on my computer or laptop as a local page but not when I place it on the router. I place the original page back and it work.
Using a rd433 Router os 3.25

Just for info I finaley have found someone interested in setting up a link and access point that can see me at -54bd from inside his shed! (with the front door open and using a 24db mesh) and he can see most of the residential section of Mt Barker that I cant see

Darren