As you can see, you have a lot of options when it comes to the paint you will use on your glass projects. The ones you choose will depend first on how serious you are about wanting to paint on glass. If you just want to give it a quick try, so with the acrylics you already have and choose an object that won't have to withstand a lot of wear and tear. Otherwise, I'd recommend that you start with one of the less expensive optional bakeable paints for starters. Get the opaques to begin with, since you are no doubt accustomed to that type of painting, But buy a couple of transparent paints as well, just to get accustomed to those.
Now find yourself some inexpensive glass - something that you don't mind ruining in case your first attempts are less than successful. Old jars for spaghetti sauce or salad dressing, even soda bottles are good. Or make it really easy and find a small flat piece of glass - an old mirror - anything that you can play around with for a bit.
Note carefully - if you are using transparent paints then you must use clear glass. The paint won't show up on colored glass unless it is a very pale tint.
Remember that if you are going to use a stencil it needs to be flexible on curved surfaces. If you want to affix it with spray adhesive, let it sit for a few moments so that it is only tacky and won't leave adhesive residue on the surface.
Also make sure you have some brushes and/or sponges handy. Next lesson we'll be talking about applying paint to glass - and you'll want to have the necessary materials handy when we start.