how to change test "Your e-mail address" the plugin subscribe ?

i have a plugin in subscribe in widget and i use in the main sidebar how to change the text”Your e-mail address” i want my own word ? and the subscribe button too change my own language?

after user subscribe it shows up the word”Thank you for your subscription! Confirmation e-mail was sent to your e-mail address!” how to change that test too?

please help

i use twenty twelve version 3.9.1 no child theme