There are many sources where you could find instructions for how to translate WordPress theme. Of course the first place where you should start is the WordPress Codex – Translating WordPress. There you could find all the information you need to translate your WordPress theme.

In one of the client’s project in which I’ve been working on I had to prepare and generate *.po and *.pot files for one of his themes and the theme framework that we are working on. I followed several steps and I’ll share with you yet another ‘tutorial’ of how to

Generate POT file for WordPress Theme

Start Poedit
– You could download Poedit from here or to install it from the Terminal if you are using *nix OS:

sudo apt-get install poedit

Click File -> New Catalog

Enter a Project name (probably your theme’s file name).

Click the Sources Paths tab at the top.

Click the New Item icon (second one, looks like a little square).
Enter the path to the directory containing your theme file (“.” tells Poedit to scan the directory that you will save the file to), press enter.
Example: /home/metodiew/projects/path-to-wp-theme/

Click the Keywords tab at the top

Click the New Item icon
Enter __ (that’s underscore underscore), press Enter

Click the New Item icon
Enter _e (that’s underscore e), press Enter

Click Okay

Choose a name for your .po file (probably your theme’s base filename)

The Update Summary window should display, with a list of strings that were found to translate, based on the keywords supplied above (__ and _e). Click Okay.

Best Practice

If you want to follow the best practice, create a folder called languages and put the translation files in that folder. Save the *.po file, and Exit the program.
Also you could make the .po file available for download (or optionally include it in the theme archive). In that way you will provide option to other people to translate your theme in other languages.

Translators will use this file to construct a *.mo file, which will be used by the load_theme_textdomain() function.

Example:

function your_theme_after_theme_setup() {

    // ******************* Localizations ****************** //
    load_theme_textdomain( 'your_theme_textdomain', get_template_directory() . '/languages/' );

    // here goes the rest of your code
}

add_action( 'after_setup_theme', 'your_theme_after_theme_setup' );

P.S. most of those instructions are taken from the Codex and you also could find many similar tutorials from many Internet resources. I just wanted to have this one in my blog, so I’ll could easily find and follow when I need to prepare translation for another themes.