translate english text already written in text editor

My website is already built in english using the jupiter theme and visual composer. I have added english text on each page via visual composer text blocks. I also have menu items and page titles which are all in english. I have tried to translate the website to dutch using loco translate and loco translate but i cant see a way of translating text that i have entered via text blocks or menu items i have created. It seems it only translates text which is in the core files. Can you tell me how i can translate text i add please