Adjust the size of the slider

I have looked for information regarding adjusting the size of the slider, but several of the responses just say to change it to box. I’ve done that and it’s not a resolution. https://www.ads-software.com/support/topic/home-page-slider-makes-images-too-large?replies=2

The slider is huge, stretching my pictures and distorting them. I’ve tried a suggested custom css but that doesn’t work.

.flexslider {
background: transparent;
background-color: none !important;
}

.slider {
padding-top: 10px;
}

I’m new to WordPress. I’m used to building in html code, so the php files are throwing me off and still trying to figure them out.