So how does this whole thing work exactly? I made an account here on beehaw, but then when I view other lemmy instances, I see some of the same posts that are here on beehaw.
And then I get a reply from this site instead, where I can't comment because I need to log in, but it doesn't allow me to? https://lemmy.ca/comment/190838
Based on my experiments, being new to this as well, it feels like each site offers the ability to create credentials, but gives you access, via their particular interface to the whole network of lemmy sites that are sharing with one another. I'm on via lemmy.world and using the Jerboa app, so I think If you can find the post on beehaw again you should be able to comment from there.
In googling around a bit I found someone made a nice analogy to email where everyone can be on different sites, but still communicate between them.
Another thing I learned from this is that apparently not all sites are necessarily connected, but that feels like it defeats the purpose.
On the point of servers not being connected - by default an instance will federate with all other instances. Admins have the ability to add a whitelist (only connect to these instances) or blacklist (connect to everything except these).
There are some unsavoury instances out there that don't mesh with the Beehaw philosophy so they're blocked.
The nice thing is you can run your own instance and federate with everyone if you don't like the idea of blocking instances. You might find others will block you if they don't agree with your content but that's their choice.
So to respond to your comment, I have to click on the "Show context" button to open up Beehaw's interface.
If I click on "Show Context", it takes me to lemmy.world where I can't respond because I need to comment. Is it bad if I've tried logging in to other instances with my credentials?
No, it isn't bad - it just won't work. Instead you need to copy the link provided in the sidebar of the community telling you to log in (it starts with a ! for Lemmy communities), click on Communities at the top of the page, paste the ! link into the search bar, and press "Enter." That should bring up the community icon with a "Follow" underneath. Click "Follow" and you are in - you can comment on threads for that community!
Probably not bad. I tried it too earlier just to see, and just stumbling around as well.
The app has helped me a bit in that it seems to hold some of the context for my account. Meaning as I move around these communities it keeps me in my context where it knows which site I'm connected via.
Links have been troublesome for me thus far though. Opening the other communities in their native interfaces instead of in the app or somehow via the site I'm logged into. Probably something to ponder on as development continues. Maybe someday the app can handle the "magic" of getting a post via a link to another site within my site's context if they are connected.