Discourse has something that SMF didn’t have - the sidebar. This is the menu on the left hand side of the screen. It’s got the most commonly used things on it like Categories, Messages, Channels and Chat.
If you don’t like the sidebar then you can hide it. Just click the three bars button at the top left of the Discourse screen. To unhide it just click it again.
If you hover over the main headings, e.g. Community, etc. then a small icon appears to the right of the heading. If it’s a ‘+’ then clicking it will start the creation of -
Community - a new post
Messages - a new message
Personal Chat - a new chat with someone (or some people)
If it’s a pencil icon then it means you can change that heading items. So clicking the pencil to the right of Categories takes you to your Sidebar Preferences where you can change the categories listed and also how you navigate using the category options. So you can put your favourite categories here for quick access. You get some default entries but you can change any/all of these to tailor the list to suit the way you use the forum.
We haven’t really explored Channels yet, but if you click the pencil to the right of Channels you’ll go to your channel configuration. Here you can join (or request to join) a channel, leave a channel you’re already joined to or create a new channel. There’s currently only one channel, boringly named General which everyone can access, but there might be some more in future.
At the very bottom of the sidebar there’s a small keyboard icon. Click on that to see a list of keyboard shortcuts that you can use in the forum. Not everyone will use shortcuts but some people like quick access shortcuts to various functions.
That’s it for the sidebar. Hopefully it’s something useful for you.