Sometimes themes or plugins might ask you to enter the post or page IDs in order to setup some options. Every post and page you create in WordPress has an unique ID number. I wrote a simple tutorial to show you how to find the post or page ID in your WordPress site.
There are two ways to find your post or page ID. Navigate to the Pages(or Posts) page and hover over the page (or post) link. At the bottom of the page you can find the link with an ID number.
Also, you can click on the page (post) link and it will redirect you to the Edit page. Then your page (post) ID number will be displayed in the address bar at the top of the page.