Good Morning Lolita,
Good questions. I typically recommend making an image that’s around 2400 pixels wide by 1200 pixels tall. That’s big enough that it will look nice on a large monitor, but small enough that it will still load quickly.
One key when picking an image is to choose one that has it’s main content close to the center, both vertically and horizontally. The hero section will crop the image somewhat on the left and right, especially on a smaller screen. Keeping the main content near the center will help that.
For the logo, the main concern is to keep the image shorter than 100 pixels tall. You can make it just about as wide as you need to. The amount of space width wise will depend on how many menu items you have. The more menu items, the less space there will be.
For the staff images, the suggested size is 405 pixels wide by 525 pixels tall.
For the products, the suggested size is 360 pixels wide by 480 pixels tall.
The posts can have any size you’d like to use for the featured image. If you want to keep them all the same size, then make sure to size them all the same before uploading them. I believe in the demo the are 380 pixels wide by 230 pixels tall.
If you have any questions, just let me know.
Thanks,
Bill