To begin, navigate to the Toolbar > Edit with Elementor > Header Dark
Or go to Templates > Theme Builder > Transparent Header > Edit with Elementor. Control the layout, conditions, rules and styles of the header template.
Please check these guides for further information:
Create Headers Using Elementor
Guide to Vamtam Elementor Builder
3. How to edit the logo image
You can edit the column and the Site Logo styles:
https://docs.elementor.com/article/368-column-overview
https://docs.elementor.com/article/453-site-logo-widget
To set the logo size, visit the Style section:
You can edit the Logo image, Site title and Tagline in Customize > Site identity:
You can check this guide for more details: Vamtam Elementor Themes: How to edit the Logo image, Site Title and Tagline?