Creating a heatmap test for a WordPress page is very easy. You just have to select the chosen page and start the test.

In Nelio A/B Testing, create a new heatmap test by selecting this type of test from the dialog that opens when you click on the button to add a new test.
On the test editing screen you set a name for your test so that it is easy to identify later. You can also add a description of what you want to try in the test. Last but not least, you need to select the page on which you want to do the heatmap test:

If the page you are looking for does not appear in the selector, check the box to generate the heatmap from a URL and enter the URL of the page in question in the input text field. Keep in mind that this URL must belong to the same WordPress where you have Nelio A/B Testing active for it to work.
When you have everything ready (as you see in the previous screenshot, it is very easy), click on the button in the upper-right corner of the window to start the test. You just have to wait for your visitors to come so that Nelio A/B Testing collects data from their behavior on the page and process the results.