Installation instructions

docs/en/020_Getting_Started/020_Download_and_Installation.md

@@ -3,3 +3,48 @@
 # Downloading The Arse
 
 The latest version of The Arsse can be downloaded [from our releases page](https://code.mensbeam.com/MensBeam/arsse/releases). The attachments named _arsse-x.x.x.tar.gz_ should be used rather than those marked "Source Code".
+
+Installation from source code is also possible, but the release packages are recommended.
+
+# Installation
+
+At present installing The Arsse is largely a manual process. We hope to some day make this easier by integrating the software into commonly used package managers, but for now the below instructions should serve as a useful guide.
+
+In order for The Arsse to function correctly, [its requirements](Requirements) must be satisfied. The process of installing the required PHP extensions differs from one system to the next, but on Debian the following series of commands should do:
+
+```sh
+# Install PHP; this assumes the FastCGI process manager will be used
+sudo apt install php-cli php-fpm
+# Install the needed PHP extensions; curl is optional
+sudo apt install php-intl php-json php-xml php-curl
+# Install one of the required database extensions
+sudo apt install php-sqlite3 php-pgsql php-mysql
+```
+
+Then, it's a simple matter of unpacking the archive someplace (`/usr/share/arsse` is the recommended location on Linux systems, but it can be anywhere) and setting permissions:
+
+```sh
+# Unpack the archive
+sudo tar -xzf arsse-x.x.x.tar.gz -C "/usr/share"
+# Make the user running the Web server the owner of the files
+sudo chown -R www-data:www-data "/usr/share/arsse"
+# Ensure the owner can create files such as the SQLite database
+sudo chmod o+rwX "/usr/share/arsse"
+```
+
+Finally, The Arsse's newsfeed refreshing service needs to be installed in order for news to actually be fetched from the Internet:
+
+```sh
+# Copy the service unit
+sudo cp "/usr/share/arsse/dist/arsse.service" "/etc/systemd/system"
+# Modify the unit file if needed
+sudoedit "/etc/systemd/system/arsse.service"
+# Enable and start the service
+sudo systemctl enable --now arsse.service
+```
+
+If using a database other than SQLite, you will likely want to [set it up](Database_Setup) before setting up the service.
+
+# Next Steps
+
+In order for The Arsse to serve users, those users [must be created](Managing_Users), and in order for the various synchronization protocols to work, a Web server [must be configured](Web_Server_Configuration). The following manual pages provide details on how to get this set up.