Basically, in MODX you would put the parts of that theme that go on every page in a MODX Template, and then put the page-specific content of each page into the Resource Content field of individual resources that all use your template. You'd have five resources with these pagetitles: home, about, contact, blog, and portfolio. The blog and portfolio pages would probably have child pages as well. The Wayfinder extra creates menus automatically based on the structure of the Resources tree in the MODX Manager. It can be used in your template to create a complete menu for the site, and/or on individual pages like the portfolio page to create a different menu for the page's children.
I use Articles for my blog, but many people think it's outdated.
You can then (optionally) move some of the blocks of HTML code in the Template into chunks (things like the header and footer) and replace them in the Template with chunk tags which will pull the content of the chunks into the page:
