I want a new paragraph every time I click on the button I created using innerhtml

I've done the correct syntax in JavaScript. I want my paragraph to only change when I click the button I created. 

```
var button = document.getElementById("createpara"); 

document.getElementById("showpara").innerHTML;

function writepara() {

    document.getElementById("showpara").innerHTML = '<p>This is IT</p>';
}

document.addEventListener("click",writepara, false);

```

I want my paragraph to only change when I click the button I created.