Here are some step-by-step instructions to translate the posts with WPML.

1) Go to the posts page and then click the translate icon

2) Select the text
3) Edit the text in the large text box
4) Click the check when you are done
5) Click complete when you are done with the whole page.

More information and tutorials on the use of WPML plugin can be found here:
https://wpml.org/documentation/getting-started-guide/#translating-without-wpmls-translation-management
https://wpml.org/documentation/translating-your-contents/advanced-translation-editor/