How does one align text after selecting it?

After typing text I want to align it right or center or left.
The align toolbar is grayed out.
How does this function work in LibreOffice?

Have you tried with the contextual menu? This is usually invoked with a right-click of your mouse over the selection or the corresponding key on your keyboard – on mine is between the right-hand [Alt] and [Ctrl] keys.

Okay. That works too. Thanks

Ctrl E, Ctrl L, Ctrl R will do the trick.
But why is are the icons grayed out?