In this first part of the Bash and Linux lab you are going to get familiar with the resources that are available online. When reading any course it's important to not only read and understand the material given to you, but also to be independent and learn on your own. After you are finished here at KTH you will need to continue learning on your own and that's why self study is a common theme at university.
To type in the ~ sign in firefox some people need to press the pagedown button.
Codecademy is very picky about how you change folders. You can not chain moving up eg ../.. and when it tells you to change into x/y you have to do BOTH steps at once.