I can try to help to the best of my abilities. However, those may be limited, as I’m only a casual user of Matrix.
You can set up an account on Matrix by registering with a server, or hosting your own. I’ve done the former by registering via the web-based Riot client, at the server
matrix.org. (There are other clients, but Riot is the most complete one.)
Riot offers the option to create a new “room” (akin to IRC channel), and also new ”communities”, which may be used to group rooms and users together. Users should be able to join your room via a link, or by searching for it. I believe you can set moderators for a room, although I haven’t investigated this much.
There’s an icon (“Show Apps”) which lets you add bridges to other chat apps. The current options are “IRC”, “Gitter” and “Slack”. Below I quote the description of the Slack bridge:
This integration bridges a Slack channel into a Matrix room. Users in Matrix appear as bots in Slack. Slack users appear as users in Matrix. To configure:
- In Slack, you must add an Inbound Webhooks and an Outgoing Webhooks integration to the channel you wish to bridge.
- Please paste the URL that Slack tells you for the Inbound Webhooks to the “Slack incoming webhook URI” below and hit save.
- Then please paste the URL that we give you for the Outgoing Webhooks to the “Slack outgoing webhook URI” and hit save.
I have never used Slack, so I can’t assist you there, but I suppose you’ll know what’s to be done, going by the instructions. Let me know should you need me to look up further info or do something to help as a Matrix user!
I believe IRC is libre. My statements concerning non-libre software are general and mostly just relevant to Slack here.