Hello, I'm new here. I've been playing guitar for a while without a strap for my acoustic guitar, I finally bought one, but I am not sure how to put it on.

I know that one sides goes to the bottom, but I am not sure how to attach the other side. It looks like a belt, with two holes attached to the strap itself. There are slots in the strap, but I am not sure how to attach it.

Have I bought the wrong kind of strap?

If your acoustic only has one strap button, then take it in and have a guitar technician add another one near the heel. There are several different options for the location of the strap button. Cost to have one installed is minimal.
Should've added that some straps are designed for acoustics without second strap buttons. This type of strap is usually attached to the headstock. I'm not a big fan of this type of strap, since it places a lot of weight at the end of the neck of the guitar. That's why I recommended having the second button added. If you know what you're doing, you can do it yourself. If you don't know what you're doing, you risk cracking the heel.