To remove the white part in-between.

Hi there,

This part?
https://www.screencast.com/t/XHbWkfmCap

If so it's coming from a page hero/header element which you can just remove:
https://docs.generatepress.com/article/header-element-overview/

Let me know if this helps :)

Thanks, it work. And can you tell me how to size the image in a good size.

Hi there,

edit the Header Element and increase the Top Padding and Bottom padding.