esmi on "making translation theme ready"

Where do I get POT file?

You have to create it using a tool like Poedit.

Where do I place the file?

That's entirely up to you. commonly it's in a sub-folder called languages. Then you need to reference it within your theme's functions.php file using something like:

load_theme_textdomain( 'my_theme_textdomain', get_template_directory() . '/languages' );