How can I optimize a homepage picture for both mobile and desktop views?

[shanabenittah]

Hii!
I am using Symmetry theme and I chose one picture to be my main picture on my home page
Looks perfect on mobile but bad on desktop
I don’t know if there is a way to fix it because of the size of the picture so I thought maybe change the size of the picture in photoshop and then upload two different pictures to the two different views (desktop and mobile).
But do not understand how to do it

thanks for any help

[NomtechSolution]

Modify the code: In the code, you’ll typically find an HTML tag or some JavaScript code that sets the background image. Replace the code with the following liquid code:

{% if request.is_mobile %}
  
{% else %}
  
{% endif %}

[shanabenittah]

thank you so much for the help

where should I find that section?