Creating the Pixel
Go to the Facebook Ads Manager. Click on the "Pixels" menu item that appears underneath the drop down menu in the top left corner of the screen.
Click on the green "Create a Pixel" button on the setup screen. Enter a name for your Pixel in the pop up box and click "Create Pixel".
That's it. You've created your Pixel! Click "Install Pixel Now" to add it to your website.
Adding the Pixel to your website
You'll be presented with a screen that looks something like the following. This is the snippet of code you need to install on your website to track pageviews, referred to as the Base Code.
The easiest way to install the Facebook Pixel on your website is to you use Google Tag Manager. This allows you to easily edit the code snippets you have on your website without having to do so by directly editing the HTML. Otherwise you'll have to directly edit the HTML files on your website, which may require the help of your web designer or developer.
This code snippet needs to be placed between the HTML <head></head> tags on every page of your website. But wait! This Base Code snippet currently only tracks pageviews on your website and you also want to track conversions.
Source: https://www.adgo.io/blog/2016/12/22/how-to-install-the-facebook-pixel-a-step-by-step-guide