Cant override the default template files

The context
I’m new to openedx platform, I’m trying to customize the platform so i started with the theme, i installed openedx using tutor, and i’m developing my theme in dev mode of tutor. I’m using tutor indigo as a starter template. i’m following the documentation of tutor and the documentation of openedx:
tutor 's tutorial for theme development ,openedx documentation for comprehensive theming .

The issue:
I have two problems i cant solve:

  • I’m trying to override openedx platform default template files, i add them to my theme directory but i get the default file.for example i added header.html to the directory theme/lms/templates/, i modified the file but the file isn’t overridden. how can i override the default theme files?

  • the second issue is that i want to add bootstrap to my project but i cant figure out how, i know there is project that integrates bootstrap to openedx (openedx-bootstrap ), how do i add it to tutor? if it’s already on tutor, how can i use bootstrap classes?

Thank you for your help