drag the icons representing the panes anywhere – experiment with edges of screen etc.
you have two sidebars – left and right – and you can build up a workspace with multiple sections on the sidebars where horizontally you can add more items
by default, the app adds one item/icon of each core plugin (and third party plugins’ icons go next to these so over time you’ll need to drag the sidebar out to make space for the new icons) but you can right click on icons (make pane active first), and using the hover editor plugin you can open another instance of them, then dock them into the workspace and by grabbing the freshly made icon anywhere again, you can have multiple instances anywhere…
if you think you have botched things up and want to start again, do the following BEFORE you do anything:
make a copy of your workspace.json file in the .obsidian folder, and rename it workspace.json.backup
then if you have made a mess or not happy with the result or anything, quit obsidian, delete the workspace.json and rename the backup to workspace.json
have fun