i've converted a wordpress plugin in the german language.

membership 1.x

i required the word what.container file and translate all lines.

next a transformed the data: enter image description here

i've submitted the file to server and changed that old one... however it stil in british... blog is within german "p_P"

can someone assist me to?!

You should not translate the .pot file (it is the supply of all translations), you need to rather copy it and title it following the textdomain specified within the wordpress plugin (presuming it's written to aid translation). If you will find other translations already made, consider the title of individuals files, otherwise search for a line such as this within the wordpress plugin:

load_plugin_textdomain('name', false, dirname(plugin_basename(__FILE__)));

here name is what you need to call your file, then the locale specs i.e.:

name-de_DE.po

then you've to compile the .po file into .mo (you will find several ways to get it done based on your operating-system) and upload it within the correct directory.