Attention: Your website must be a Joomla.org and not a Joomla.com website.
Login to your MailMunch account, and follow the few easy steps mentioned below.
Step 1: Sign in to your MailMunch account, and choose your site.
Step 2: Click on the Site Settings tab present on bottom left of the screen.
Step 3: Click on the GET SITE CODE button on the top right corner of the screen.
Step 4: Copy the site code.
Step 5: Sign into your Joomla account. In your Control Panel, click on the Templates option located under the Configuration heading present in the left column.
Step 6: Click on your active site template name, it is indicated by a star next to the name. As shown below, it is Protostar in this case.
Step 7: Click on index.php from the file list available in the left column of the screen.
Step 8: Paste the MailMunch Site Code that you copied earlier, inside the head tags within index.php. Click on the Save & Close button.
That's it! The forms that you have created in your MailMunch account are now live on your Joomla site.