osCommerce has changed the way to create your own infobox in v2.3x. Majority of the links on internet are for older versions and which does not work on v2.31. If you want to create your new info box in 2.3x which modules now then follow the below instructions.
- Copy catalog/includes/modules/boxes/bm_information.php and give it a new name.
- Edit that file and change bm_information to your new box name throughout that file.
- Change all of the constants that include _INFORMATION_ to include your new name instead. Keep them in all caps.
- Change the content to what you want in your new box. If you are using links to new files, keep the same format as the links in that box. The part that generates the box is in the execute() method.
- Copy catalog/includes/languages/english/modules/boxes/bm_information.php and give it a the same name as you did the file in step 1.
- Make the same changes to the constants in this file that you made in step 3.
- Upload your two new files.
- Go to your store Admin > Modules > Boxes and install your new module. Give it a sort order that will place it where you want it.
Feel free contact me for detailed instructions or if you want a video tutorial.