One of the greatest questions in physics right now is the matterial/energy composition of the universe so it's interesting you should ask this, perhaps that's why you did? Basically this whole question boils down to the "shape" of the universe. So what do I mean by this? Well scientists picture the universe as sort of like a balloon that is being blown up. The surface of the balloon is 2D and our universe is 3D (minus time) so it's not a perfect analogy but it works for now. The surface of the balloon actually represent empty space itself. On this surface is all the matter in the universe, stars, galaxies, dust, etc etc... We've known for some time now that this balloon is continually expanding. If you draw little dots on a balloon and blow it up those dots will all move away from each other. This is the expansion of the universe and those dots represent galaxies moving away from each other, something we see with our telescopes.
So here's a fact that most people probably know, matter/and energy "create" gravity. I put that in quotes because it's kind of simplified but it will do. So matter is attracted to other matter. Galaxies are attracted to other galaxies. So if there are all these galaxies out there that are made of matter they must be attracted to each other, and they are! Well if all of them are attracted to each other doesn't that mean that they will pull each other together, stop the expansion? Scientists actually asked this question for many many years. IS there enough matter in the universe to STOP the expansion of the universe (stop the balloon from expanding) and start to pull it all back together again ( start shrinking the balloon). Well scientists have been looking at this question for over a decade now and they came to a STARTLING conclusion some years back. Not only are the galaxies NOT slowing down. The galaxies are seeping up! The model balloon is being balloon up at a faster and faster rate! WTF is doing the blowing so to speak!? Well some form of energy must be responsible because it takes energy to do this. So they posited a previously unknown form of energy DARK ENERGY which is responsible for this.
It turns out that there is another question. Question #2. Einstein's general theory of relativity describes gravity to a startling level of accuracy and has been verified time and time and time again. So scientists were startled to discover, some time in the 90s I believe, that galaxies weren't spinning the way they should be. In fact they didn't interact with each other in clusters they way they should be either. Basically when they added up ALL the matter they could find in galaxies they couldn't account for the way they were moving. Einstein's equations said they should be moving much differently for the amount of matter that we were seeing. All the galaxies we see are moving as if there is MUCH MUCH more matter there than we can account for. Since they can't find anything wrong with relativity, I'll leave string theory out of this, they said well there must be matter there that we can't see. They call this DARK matter, NOT to be confused with the DARK ENERGY above. Dark mater is much more like regular mater, it interacts via gravity, we just can't see it.
Now the 3rd piece of the puzzle E=MC^2. This means that matter and energy are one and the same and are interchangeable. So when you ask the question what is IN the universe. Answering X amount of matter or Y amount of energy is basically the same thing since the 2 are convertible. So scientists usually talk about the ENERGY or matter/ENERGY content of the universe by which they mean photons, and protons, ants, and people, whales, and hydrogen, DARK matter, and DARK ENERGY are essentially all just forms of energy.
So...
to rephrase the OPs question. What is the matter/energy content, or breakdown, of the universe? From what we know so far is breaks down like this:
4.9% ordinary matter
26.8% dark matter
68.3% dark energy. (these numbers from wiki)
So only 4.9% of the universe out there is stuff you and I can relate to in any way shape for form.
Feel lonely?
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