Hi! I feel your pain- I struggle to get my compost hot- though I've succeeded a couple of times! (best feeling ever!)
I think your issue might be mass. The bin basically needs to be full for there to be enough mass for the center to heat up. Otherwise, heat is lost too quickly and there is not enough microbial activity.
If your C:N ratio is about 50:50-I think thats a good aim. I would also suggest leaving your pile for a few days at a time- especially if you can build up that mass. Then turn it when you think the heat level at the center has peaked.
Check out my blog for advice on beginners gardening if you are at all interested. Good luck with your compost.

Here is a link that might be useful: Garden Geek's Geeky Garden Basics

Did you really mean 3-4" (as in inches)?

If you did, I would say not to worry about it getting hot just yet. You do need more stuff first.

Just keep adding to it. A general rule of thumb that I follow, with no particular measuring at all: if it's too wet, add more browns. If it's too dry, add more greens or water.

As for smell, I also try not to have a rotting smell. That also means to add more browns. But I want a kind of moist smell, so that means to add more greens or water.

So those are the two indications I use, without getting all into measurements of greens and browns.

I also try to have enough browns so that any new greens that I add could be covered, and not visible. This is the idea that the greens would be inside the pile, getting worked on, instead of outside the pile, attracting flies and rodents. The reality is that the pile will attract bugs and pests, but as long as I don't actively see them or smell rotting scraps, then I think I'm doing a good job of covering up all the stuff.

Also, you can mix it up every 1-2 weeks and be fine, not having to do it every day.

Congrats on starting a compost bin! First and foremost, remember that composting is the human management of the decomposition process. Translation: The stuff in your compost bin is gonna decompose regardless, so you can't really be doing anything wrong! Your involvement simply speeds up the natural processes.

So, the ideal C:N ratio is 30:1 by weight, but that's hard to measure, so I was taught that I should shoot for anywhere between 20:1 and 50:1. It's difficult to know exactly what your C:N ratio is at any given time, but a good rule of thumb is to try to keep a proportion of 2-3 volumes of Carbon to 1 volume of Nitrogen. A 50:50 ratio will eventually compost, but it'll take a while and you might have a pest problem. BTW, covering your greens with your browns will keep the flies away.

Like another poster said, think of your Carbon as the browns. This includes things like newspapers, dead leaves, paper, and grass clippings. Think of your Nitrogren as greens. These include food wastes and manures.

Also, how often you turn the pile will determine how long it takes to compost. Turning every day could reduce compost times down to a month. Compost that's never turned could take a year or more to mature.

Lastly, I agree with the other posters, your pile is currently too small to worry about heat. Huge piles can reach and maintain optimal temperatures for a week, but small piles usually only hit those high temps for a day or two.

Just keep turning it and you'll be fine! Keep us updated!

Hope the composting is going well! There is a soil/compost/mulch forum here, if you've developed any more questions.