I am designing a private site for my Business and I am having Issues with pictures fitting on the pages

As I am building our site, I haven't gone live yet, because all the pictures I import are either to large or to small therefore they don't fit the window or they are blurry once added. There isn't anywhere to adjust the size of the pictures on the site. I don't want to crop them because they need to be seen. Can someone help? Thanks,

You use spacer blocks to adjust them.

https://support.squarespace.com/hc/en-us/articles/206566727-Resizing-an-image