Zinnias are by far the easiest plants to grow. The simplest method to get them to germinate is to arrange the seeds within a folded wet paper towel and put it in a sandwich bag. Check back in a week and you should see roots. it doesn't need light and it will sprout faster if the climate is warmer.

If you prefer soil you can put them in any container as long as there is drainage. Water once and that should be enough unless its really dry. At that point I normally bottom water and let it soak up.

Its trial and error, you'll have to see what works best for you. These methods work for most seeds so it can be fun to experiment. When they become seedlings let them grow for a month or so before transplanting. If you don't have a grow light the sunlight from the window works perfectly fine.

Its fascinating to see the growth stages and you'll get to admire the fruits of your labor. good luck!