Extract the folder with indoeuropean-translator-widget.php and indoeuropean-translator-widget-menu.php into your wp-content/plugins folder (or a subfolder)
Activate one of the plugins in WordPress (under "Plugins"), the general one (with vertical and horizontal versions) or the menu version.
Add the widget to your page (under "Presentation" -> "Widgets")
4.1. If you have activated the general widget, set the options to select which one is your blog's main language or the language of the texts that your visitors will try to translate. From that main language, select (only ONE checkbox!) :
4.1.1. "Horizontal" to keep the languages on the same line, separated by dots;
4.1.2. "Vertical" to create a list of languages.
4.2. If you activated indoeuropean-translator-widget-menu.php, select the box with your blog's language.
Requires: 1.5 or higher Compatible up to: 2.8.5 Last Updated: 2009-10-23 Downloads: 8,433