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?
Editing the header for mobile resolution
Switch between Desktop, Mobile or Tablet views by clicking on the corresponding icons on the bottom of the panel and edit the content dedicated to the corresponding resolution:
You can also check this instruction: https://elementor.com/help/mobile-editing/