Translate Theme
Simple & Elegant includes a simple-elegant.pot file in /wp-content/themes/simple-elegant/languages/. Open it with translation software such as Poedit, translate the strings you need, and save the .po and .mo files with the appropriate names. For example, to translate into German, save your files as de_DE.po and de_DE.mo. See Installing WordPress in Your Language for more about file naming.
Then open wp-config.php in your WordPress root folder, find the line defining the language and set it to the language you want.
Example: translating into French
Step 1: Open wp-config.php in your WordPress root folder. You’ll need an FTP client or a file manager to do this.
Step 2: Set your site language to French. On modern WordPress, you can simply choose the language under Settings > General > Site Language. (On older versions, edit the WPLANG definition in wp-config.php, e.g. define('WPLANG', 'fr_FR'); — for German it would be define('WPLANG', 'de_DE');.)
Step 3: In your theme, copy simple-elegant.pot to fr_FR.po.
Step 4: Open fr_FR.po with Poedit, translate the strings, and save the files as fr_FR.po and fr_FR.mo in the same simple-elegant/languages folder.