Judging the size of the pot from the photo, I'd say 3 or 4, depending on the size of the plants you'll find.

But it all depends on the actual sizes! Put as many as feels right when you have everything in front...if it feels too crowded, it probably is. And if it feels too sparse... either put one more in or wait for it to grow!

You can also propagate by cutting the stems and putting them in soil, they will grow new plants pretty easily! It will take some time, but it's a good way to save money

Since you are new to plants, you will probably be better off skipping the seeds and starting with a full plant instead...seeds tend to be more difficult to grow successfully into plants and it may be frustrating for a first timer!

A pothos could be a good choice, they're cheap, they tolerate very low light and can thrive on neglect (and if you're on a budget can be easily propagated, which is always fun)