☞ Answer

Mailerlite, is an email marketing tool (if you don't know). It's a difficult one to answer with more specifics as I don't know what stage everything is at.

Let's assume you have your lead magnet already created and an automation in Mailerlite to deliver the lead magnet via email. So all that's left is to connect Mailerlite to WordPress. 

There are two main ways to go about this

1. Mailerlite Plugin
   The official Mailerlite plugin, MailerLite – Signup forms (official), is available for free in the WordPress plugin repository. Install and activate that.
   
   
   Then back in Mailerlite, create a sign up form and it will automatically appear in WordPress (via the plugin) for you to add anywhere you want.
   
   
2. Embed a Mailerlite form
   If you don't want to use a plugin, you'd still create the form in Mailerlite. It's the Embedded forms option you want to select.  Once created, you'll see a tab for the code you need to copy and paste where you want in WordPress. You'll need to use a HTML element in your page editor.

There's a 3rd wildcard option. You can use a non-official form plugin if you already have one on your website. For example, I use Formniator for my contact form. That also integrates with Mailerlite so I could just use that instead of installing the Mailerlite plugin as an additional thing. 

Want the video?

This was part of a live Q&A and my response starts around 8:40.