Often you will want to use a WordPress theme that is not in your language. If you happen to know both the language the theme is in and the language you would like it to be in, there is an easy way to translate the theme yourself.
A couple notes before we begin:
In your WordPress administration area in the main menu go to Tools > Localization.

On this page look for the name of the theme you want to translate. For our examples we’re going to use the Yamidoo PRO Magazine theme.

Once you’ve found the theme you want to translate, look to the right. You should see a link titled “Add New Language“.

Click on it and a little window will pop up. You will see a long list of different languages with radio buttons next to them. Click on the radio button next to the language you want to translate your theme into and click on the button labeled “create po-file“.

You will notice a new language item appear next to your theme’s name. There will be a link titled “Rescan“; click it.

In the little window that pops up click the “scan now” button and then click “finished” when it’s done scanning.

Now, right next to the “Rescan” link is a link titled “Edit“.

Click on this and you will be presented with the translator page. You should see a list of strings from the theme that are translatable. Next to each string is an “Edit” link.

Go through the list clicking on the “Edit” links and inputting your translated strings in the provided input areas and clicking “Save” or “Save & Next“.

Once you’ve completed inputting your translated strings look at the top of the page. You should see a button labeled “generate mo-file“.

When you click on it you will notice the timestamp next to “last written” has updated. This means the translation file was saved successfully.
If you completed all of those steps correctly you will now have a new language file in the “languages” sub-folder of the theme you just translated. You can just leave it there for your own personal use, or, you can create a copy of it to distribute to the community. Giving back to the community is a great way to say thanks for the work put into the development of these themes.
If you would like to use this translation with your theme you will need to edit your wp-config.php file. In that file you should find a line like this:
define ('WPLANG', '');
You will need to add the language code for your translation to this line. For example:
define ('WPLANG', 'ro_RO');
This would enable a Romanian translation for your theme.
As you can see, there are a few steps to follow to create your own translations but, once you figure out how it’s very easy to do. Hopefully this tutorial will help you get started.