How do I add 3 columns under the header image in Minimalist Blogger X, like on the demo?

1. Go to Appearance > Widgets

2. At the header widget, insert a “Column” block and choose 33 / 33 / 33

3. As the first block inside your column block, add a “Heading” block and write in the headline.

4. Add any other content below you want inside the column, for example a paragraph:

5. Click the blue Update button in the top right corner.

The result will look like this: