Different from Facebook.
Facebook was designed to create a network of permitted people. Twitter is a form of blogging, but reduced to 140 character snippets. You can restrict what people see, or let it be open to the public. As you wish. You can gather followers (people who receive your posts) and follow others (read their posts).
The secret, as with anything published, is to have something genuiinely interesting to say, and say it succinctly. Don’t post “Have been to bog. Bum sore”. Post something interesting and valuable. Accept that, if you have nothing to say, you need not be obliged to say anything.