image size in slider

Hi I’m using the PRO version of your theme, and I can’t figure out the right size for the images on the slider. Even dough I’m uploading the imae with the same size of the slider (962 x 469) they get all pixelated and blurry!! Can you please tell me what is the right proportion?

Here is the link to my webpage https://vimesports.com/amfa

Thanks in advance!