After you created your account, please add the support forum to your account. If you have questions or problems you can ask there.
If you connected to an existing server you can have a look at the community page of your server. There you will find postings of people of that server or (depending on the server settings) all public posts that are known to this server. From the community page you can connect to people who you find interesting.
There is a public directory of users where you can search for other people based on name, location or interest.
A good place to find other people are the forums. They are discussion places for a specific topic. At the public directory you can search for forums as well.
To understand the way that Friendica is working please have a look at the help pages at your server.