You will read various mentions of 'templates' - this is in effect mainly the home.php and page.php of your theme. There may be variations between themes with navbar.php and head.php affecting the top of the page - and footer.php ... the foot. There is logic at work here
The rest depends largely on your html skills - and to some extent php. Being able to use your browser console also really helps to identify element locations.
Not knowing your skill level I am cautious to assume or over detail. I hope this gets you started.
best - kusalo
