You can create and manage your translation jobs from your WordPress admin
Creating Translation Jobs
Go to your posts or pages list
In the Bulk actions dropdown, select Bulk Translate
Tick the checkboxes of the posts or pages that you want to translate
Click on the Apply button beside Bulk Translate
This will create a translation job, that can later be imported into the languages that you have configured in MultilingualPress.
Manage Translation Jobs
Go to Locale > Jobs
Here you can view, or delete an existing translation job
Import Translation Jobs
Go to Locale > Jobs
Select the translation job that you want to import
On the translation job information box, click on Import
This will update the posts indicated in the translation job with the corresponding translations based on the matching language codes.