Hello
To add gallery images follow the instructions below
Go to dashboard >> gallery >> add new >> set title >> set featured image from the right side panel >> click on publish to save changes
Repeat these steps to add more gallery images
Then go to dashboard >> pages >> add new >> set title as gallery >> copy and paste this shortcode [GALLERY] in the description >> click on publish to save the changes
Now to make it appear on the menu go to dashboard >> appearance >> menu >> add Gallery page from left to the primary menu on right >> click on save changes.
The feature to add gallery section on the front page is not available on this theme you may check the demo on our website.
Thank you