There are several options:

1. You can edit those in directory module named "Boxes"
Module usage is self-explanatory.
Images should be at least 200px x 200px.
In any case, we will cut and resize it for you, but if you want to control image quality, make it exact size. If you want to control at least its appearance, make it to be sqare.
Use tag <sys:dir-items mode="list" order-dir="asc" order-by="order" design="boxes" directory="DIRT2"/>

2. You can use Events section of News module
Use tag <sys:news-list order-dir="asc" order-by="release_date" limit="4" path="/news/detail" content-design="content" display-content="no" design="boxes" news-type="SYS3"/>

All those tags are in CMS by default, so you just comment out/uncomment it in content area "Main Content".

Colors are driven with CSS colors: color1, color2, color3 and color4