php - Searching for information about using info from form -

i modding system. , need information. situation - have got login form, , have got index file checks inputed data if ( username, password ). have created new select-box next inputs like:

username:</p> password: </p> language: select box </p> 

i understood index.php file checks if username , password good, checks ain't using info... so, in order use language select box need use info not check. how use select-box value? tried doing $_post['language'], doesn't help.

here index.php file https://jsfiddle.net/e40bsxox/1/

here html file https://jsfiddle.net/fd8x94j2/1/

in html file code have given select field name 'kalba'. in php file selected value using name as, in html file,

<select type="language" id="kalba" name="kalba" class="text">     <option value="lt_lt" selected="selected">lietuvių</option>     <option value="en_us">anglų</option> </select> 

in php file use

echo $_post['kalba'];