diff --git a/enable_user_sudo.md b/01_enable_user_sudo.md
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rename to 01_enable_user_sudo.md
diff --git a/install_nginx.md b/02_install_nginx.md
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rename to 02_install_nginx.md
diff --git a/03_nginx_intro.md b/03_nginx_intro.md
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+# Nginx Intro
+
+The main folder of nginx is found under:
+```text
+/etc/nginx
+```
+
+Check the complete folder structure (incl. subfolders):
+```bash
+sudo apt install tree
+tree /etc/nginx/
+```
+
+## nginx.conf
+* This is the main configuration file. It includes settings like logging, configuration of worker-processes and includes other configuration files.
+* This is the first read configuration file (from top to bottom).
+* Files included via `include`, are inserted at the location of the directive.
+* The scope of settings can either be: `http`, `server`, `location` (wide to narrow). Some settings are allowed at multiple scope level. A similair pattern applies for sites that can be general (all domains), or more narrow (specific domain). Settings in a narrow scope overwrite settings in a wider scope.
+* conflicting settings within the same scope are rejected, sometimes ignored (sanity check on startup). But anyhow those conflicts can be identified via `nginx -t`.
+
+## conf.d
+Folder for configuration files. All files ending with `.conf` are automatically loaded by nginx.
+Allows better structure and delegations.
+
+## sites-available
+Used for site (domain) specific configuration files (virtual hosting). Configurations in `sites-available` are **ignored** by nginx.
+
+## sites-enabled
+Used to enable the sites defined in `sites-available`. It should contain only symlinks.
+
+## modules-available and modules-enabled
+Used for nginx modules (extensions).
+
+## Configuration structure
+Nginx uses following hierachical structure:
+
+```nginx
+# --- main context (global) ---
+user nginx;
+worker_processes auto;
+
+events {
+ # --- event-context ---
+ worker_connections 1024;
+}
+
+http {
+ # --- HTTP-context (Webserver-Settings) ---
+ include /etc/nginx/mime.types;
+
+ server {
+ # --- server-context (Virtual Host / Website) ---
+ listen 80;
+ server_name example.com;
+ root /var/www/example.com;
+
+ location / {
+ # --- location-context (URL-Handling) ---
+ try_files $uri $uri/ =404;
+ }
+ }
+}
+```
+
+# Document-Root
+per default the document-root is defined (in nginx.conf) under:
+
+```text
+/var/www/html/
+```
+Best-practice to generate a custom-directory within `/var/www/` per domain. E.g. the website `example.com` would be:
+
+`/var/www/example.com/`
+
+# Logging
+default folder for nginx log files is:
+
+```text
+/var/log/nginx/
+```
diff --git a/04_hello world.md b/04_hello world.md
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+# hello world
+instruction to prepare nginx site configuration
+
+## nginx site configuration
+
+the site configuration is created within `/etc/nginx/sites-available/`
+
+```bash
+cd /etc/nginx/sites-available
+```
+
+create a new file for the domain...or easier, copy the exisiting one:
+
+```bash
+sudo cp default *my_domain*
+```
+
+and edit the file:
+
+```bash
+sudo vi *my_domain*
+```
+
+```nginx
+server {
+ listen 80;
+ listen [::]:80;
+
+ server_name *my_domain*;
+
+ root /var/www/*my_domain*/;
+ index index.html index.htm index.nginx-debian.html;
+
+
+ location / {
+ try_files $uri $uri/ =404;
+ }
+}
+```
+
+
+## folder structure
+
+change to directory `/var/www/`:
+
+```bash
+cd /var/www/
+```
+
+and create a subfolder for the own domain/website:
+
+```bash
+sudo mkdir /var/www/*my_domain*
+sudo chown www-data:www-data /var/www/*my_domain*
+```
+
+## create hello-world index.html
+
+```bash
+sudo vi /var/www/*my_domain*/index.html
+```
+
+```html
+
+
+ Welcome!
+
+
+ Hello World!
+
+
+```
+
+```bash
+sudo chown www-data:www-data index.html
+```
+
+## enable, verify and restart
+
+enable the new site:
+
+```bash
+sudo ln -s /etc/nginx/sites-available/*my_domain* /etc/nginx/sites-enabled/*my_domain*
+```
+
+validate configuration:
+
+```bash
+sudo nginx -t
+```
+
+restart nginx:
+
+```bash
+sudo systemctl restart nginx
+```
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