In DNN, you have a specific URL for installations, upgrades, etc. which can be found here:

http://www.website.com/install/install.aspx

You can add various parameters to the URL for performing some tasks.
These are:

• ?mode=install
  Will install DNN (if not already installed).
   
• ?mode=upgrade
  Will upgrade DNN (if there are any upgrades for DNN).
   
• ?mode=addportal
  Will add a portal to DNN (only works if the right files for this are set up under /install/portal/ folder).
   
• ?mode=installresources
  Will install resources like modules, skins, language packs if they are set up correctly under the install folder (for skins in the /install/skin/ folder, for modules in the /install/module/ folder etc.).
   
• ?mode=ExecuteScripts
  Will execute scripts which are set up in the /installe/scripts/ folder.