Be kind to yourself, this is quit technical. In a nutshell

1. Integrate Mailchimp + Leadpages.  Go to Mailchimp >> Use the dropdown at the right hand corner >> Account >> Extras >> API code >>copy that >> Create a list in Mailchimp for this leadmagnet

2. Go to leadpages .>> go the dropdown menu on top right hand side >> click integrations >> tick Mailchimp >> put in API code and integrate

3. Create a "Thank You" page >> Templates >> Thank you >> Hit save + publish and get the link

4. Create your landing page >>> template >> select >> edit the page + use your colours >> click on the button ie "Register now" and you will get the box where your dream client puts in their email address >> Edit this box >> on left hand corner select integration and select the list you created in Mailchimp (or the system you are integrating with) >> click on the "Thank you page" and unselect default and use the link created from your thank you page