Pleroma is an OStatus-compatible social networking server, compatible with GNU Social, PostActiv and Mastodon. It is high-performance and so is especially well suited for running on low power single board computers without much RAM.
Log into your system with:
ssh myusername@mydomain -p 2222
Using cursor keys, space bar and Enter key select Administrator controls and type in your password.
Select Add/Remove Apps then pleroma. You will then be asked for a domain name and if you are using FreeDNS also the code for the domain which can be found under Dynamic DNS on the FreeDNS site (the random string from "quick cron example" which appears after update.php? and before >>). For more details on obtaining a domain and making it accessible via dynamic DNS see the FAQ. Typically the domain name you use will be a subdomain, such as pleroma.mydomainname.net. It will need to be a domain which you have bought somewhere and own and not one of the FreeDNS subdomains, otherwise you won't be able to get a SSL/TLS certificate for it.
The first thing you'll need to do is register a new account. You can set your profile details and profile image by selecting the small settings icon to the right of your name.
Once you have done that then you can disable further registrations from the Administrator control panel by going to App Settings then pleroma then Disable new account registrations. This may take a while because the app gets recompiled afterwards.
Mastodon user interface
If you prefer a Tweetdeck-style user interface, similar to Mastodon, then once you have registered an account navigate to /yourpleromadomainname/web and log in.