How do I color block half of a page?

Hey, I am struggling to color block half of my page. I will provide an image of what I am trying to create but am not able to figure it out. I have tried messing with borders of div block but then I can’t put an item on top of the border or don’t know how.

Please let me know any ideas you have.

Here is my site Read-Only: (Webflow - Service Pages)