Hello,
Find the page Portfolio and translate as you do with other pages. Then navigate to the projects and create translations for each project.
As for the Header:
1. Create a separate header in the language you need.
2. Take the Header ID http://prntscr.com/lwox9s
3. Navigate to WPML Strings Translation and insert into the search http://prntscr.com/mqiqp3
Best Regards