Use own Bootstrap Theme

There are many bootstrap themes out there, the most popular themes are made by bootswatch.com

So the first thing you have to find out, is the type of bootstrap theme.
There are two at all:

Type 1: The themes completely replace the bootstrap file
Type 2: The themes working next to the bootstrap files

If you are unsure, just try to replace the bootstrap file and if mostly all elements look crap, its the second type 😉

Below are the step you have to take, when your theme is type 1:

• If you only have a bootstrap.css file (its the not minified version), just rename it to bootstrap.min.css
• Use your favorite ftp manager (e.g. Filezilla) and move into /your-phpBB-installation/styles/comboot-free/themes/comboot/</li>
• Place your theme file named bootstrap-theme.min.css (!important) into the comboot folder
• At least you have to edit some configs. Therefore open /your-phpBB-installation/styles/comboot-free/template/config.html and change the variable DEFINE $THEME_FILE = 0 to 1, so the line looks like DEFINE $THEME_FILE = 1

If your theme is type 2, follow these steps:

• Take your downloaded bootstrap.min.css or bootstrap.css (it also possible, that the name differs) file and rename it to bootstrap-theme.min.css
• Use your favorite ftp manager (e.g. Filezilla) and move into /your-phpBB-installation/styles/comboot-free/themes/comboot/
• Replace the current bootstrap.min.css with your theme file