How can I recreate my HTML page with custom grid layout (blocks spanning rows and columns) in Wordpress?

I'm attempting to recreate my website on Wordpress in the style of my old HTML code, and I don't know how to recreate the grid of my old homepage here: http://selamawit.com/index-old.html

The problem is that while it's a grid, the blocks span multiple rows and columns. Is there a (free) wordpress plugin I can use or is there a way to upload custom HTML code in order to recreate this layout?