How to type C-M?

Particularly, I am after this command -

[![enter image description here][2]][2]

from https://www.gnu.org/software/emacs/manual/html_node/emacs/Indentation-Commands.html

First attempt

1. Select the text
2. Use the combination Ctrl-Alt and Ctrl-Alt GR but I don't see any effect.

Second attempt

1. Select the text
2. Press at the same time keys marked with a red square on the keyboard map

No effect

[![enter image description here][1]][1] [1]: https://i.sstatic.net/jXlIG.png [2]: https://i.sstatic.net/ojhb0.png

How to type C-M?

Particularly, I am after this command -

from https://www.gnu.org/software/emacs/manual/html_node/emacs/Indentation-Commands.html

First attempt

1. Select the text
2. Use the combination Ctrl-Alt and Ctrl-Alt GR but I don't see any effect.

Second attempt

1. Select the text
2. Press at the same time keys marked with a red square on the keyboard map No effect

By asking a key description (type C-h k followed by the relevant key combination) I really get the correct reference:

but why I don't see any indentation?

How to type C-M?

Particularly, I am after this command -

from https://www.gnu.org/software/emacs/manual/html_node/emacs/Indentation-Commands.html

I try the combination Ctrl-Alt and Ctrl-Alt GR but I don't see any effect.

How to type C-M?

Particularly, I am after this command -

[![enter image description here][2]][2]

from https://www.gnu.org/software/emacs/manual/html_node/emacs/Indentation-Commands.html

First attempt

1. Select the text
2. Use the combination Ctrl-Alt and Ctrl-Alt GR but I don't see any effect.

Second attempt

1. Select the text
2. Press at the same time keys marked with a red square on the keyboard map

No effect

[![enter image description here][1]][1] [1]: https://i.sstatic.net/jXlIG.png [2]: https://i.sstatic.net/ojhb0.png