In order for content to be valuable for people, it has to be either educational, entertaining or inspiring. If you could get all of them, that would be ideal, even though that is difficult.
If you're making content online, you should aim to get at least one of the three.
Usually, to be educational is the easiest because all you need to do is a bit of research on the Internet about something and write about what you learned. You can build an audience just by teaching what you just learned.