If you type some keywords in the address bar (also known as location bar) in Firefox and press enter, it will perform a search for these words.

To change search engine, or configure the behaviour, type about:config in the location bar, and search for keyword.URL, update to match your needs.

To use the DuckDuckGo search engine:
https://duckduckgo.com/?q=

Use Google, with "I feel lucky" effect, going directly to the best matching result:
http://www.google.dk/search?ie=UTF-8&oe=UTF-8&sourceid=navclient&gfns=1&q=

Just go to the Google result page:

From your terminal, run this command: sudo apt-get install gnome-shell

Reboot your computer, click on the little Ubuntu icon next to your login name and select select 'Gnome Classic (No effects)'.

To install the Danish dictionary, run this command, from your terminal: sudo apt-get install hunspell-da

Restart LibreOffice, and from Writer, choose Tools -> Options... click Language Settings -> Languages in left menu. Under 'Default languages' - 'Western' select 'Danish'.

From this page: http://wiki.documentfoundation.org/DA/Dansk_ordbog

Installing a web server is very easy in Ubuntu, just enter a few lines in the terminal: There is no need to install and configure each part of a LAMP (Linux-Apache-MySQL-PHP) installation individually. You can also install other programs this way. The downside is that all components are installed automatically, and not reviewed by you. But as long as you only use the web server locally (localhost or 127.0.0.1), and don't open up for access from the Internet, it should be safe.