The main sidebar is made of 5 sections
Highlighted in magenta, contains the logo and the user menu. Click on the logo to go to the home page. Click on the 'hamburger' icon to open the user menu, from where you can open the recent documents and reach various pages in the website.
Highlighted in green. Each icon opens a functions panels. You can open the functions panels clicking on these icons, and close them clicking again on the icon on the left, or clicking on the 'x' icon in the top right corner of each of them.
Highlighted in yellow. This is where open panels will show up.
Highlighted in blue. This is where you will find important functions that need to be accessed easily and frequently, like the zoom, or the save function.
Highlighted in red. This section at the bottom displays short instructions for anything you have your cursor on at any given moment. For instance in the picture the cursor is hovering the 'Palette' panel icon and the instruction give a brief explanation about the content of the panel.