How to link to a sign up to read more ….?

I have downloaded the WP theme Newschannel and I like the way it features all our blog articles, presented by pictures and the blog article title.
This is supposed to be a membership based blog, and I have MemberPress.

My question is:
How and/or where do I make sure the featured boxes on front page are getting linked to a post page where you can read parts of the article, but have to sign up to read it all … ?
When I click on the front page’s featured boxes now, the blog article comes up in full – but I want it to be just the first part, and then a sign up form.

Thank you for any advices, still a newbee …