How to improve banner photo quality and add moving text bar on Warehouse template?

> I made my banner photo in canva, with canva the quality is very good! if I upload this in my store the quality is bad, how do I solve this? my template is warehouse. also the format of canva is never the same as in my warehouse... how do i solve this? I would also like to have a moving text bar at the top of my page, how do I do this? I would also like to have my social media icons at the top of the page, how do I > >

I made my banner photo in canva,
with canva the quality is very good!
if I upload this in my store the quality is bad, 
how do I solve this? my template is warehouse. 
also the format of canva is never the same as in my warehouse...
 how do i solve this? I would also like to have a moving text bar at the top of my page,
 how do I do this? I would also like to have my social media icons at the top of the page,
 how do I do this?
Please help im getting crazy

thanks in advance.

@Glennbosmans - can you share your site link?

https://media-king.eu/

@Glennbosmans - square iamge is creating the issue, background css is set to cover the entire banner space and hence it is been stretched, original image width is not enough - https://cdn.shopify.com/s/files/1/0607/7926/6211/files/SPLASHY_DEALS_1400x.png?v=1646520816

I'm sorry but I don't understand all this
Thanks for your help

@Glennbosmans - create image with recommended banner size in customize settings

Stay the same problem

@Glennbosmans - looking better than before

Yes thank you for help, but still not sharp

I can’t present it to by buyers on that way

My buyers *

@Glennbosmans

create image with recommended banner size in customize settings made with photoshop

It all Don t work, this is a reason to quit work with shopify I buy I theme for 300dollar and the quality of my pictures is ■■■■■ I put 100 hours in te shop… very sad

@Glennbosmans - is this the way you want?