The command line is always active.
Just start typing something and your text will appear there.
You can type in any word you like, such as company names (i.e. Amazon), a single currency (i.e. EUR), currency pairs (i.e. EURUSD, GBPUSD), generic words (I.e. cars, computers), and see what option you will get.
There are many different ways to study the charts and you can find brief descriptions of available chart studies in the 'Browse' option.
You can type 'HELP' in the command line to look for instruction guides made by Bloomberg.
