first thing. you have posted in the phpbb 3.2 forum and you do NOT want to install phpbb 3.2 yet because it is still being tested and has not been released.
having said that, to install 3.1.10 click on the downloads button in the menu at the top of this page.
download the current full version zip file to your computer.
unzip it to your computer, you will have a folder named phpBB3
using ftp only, upload that folder to your server ( usually to the public_html folder or the htdocs or www folder, whatever your host provides for you. )
using your hosting control panel, create a new blank database with a username/password.
now, visit http://www.appnas.com/phpBB3
in your browser and the install will come up.
fill in the blanks, click the buttons and follow instructions and you are done.