First, get updates.
sudo apt-get update
Now install the web server, Apache:
sudo apt-get install apache2
After this is finished, you should try to hit your Raspberry Pi with your browser (type in the address of your Pi and hit enter):
We also need php.
sudo apt-get install php5
sudo apt-get install php php-gd php-mbstring php-dom
And we need the sqlite plugin as well as unzip if you don't have it already:
sudo apt-get install unzip php5-sqlite
sudo apt-get install unzip php7.0-sqlite3
Now restart the webserver:
sudo service apache2 restart
And do:
sudo su cd /var/www/html git clone https://github.com/kanboard/kanboard.git cd kanboard && git checkout v1.2.5 && cd .. chown -R www-data:www-data kanboard/data service apache2 restart
Now try to hit http://<your pi IP address>/html/kanboard from your browser, if you were successful you should see: