modify the visualizations of the categories

I need an email to tell you what I want, and send you an image. I want to change the table of the visualizations of the categories, the content (the paragraphs and writings within the post) disappear them, I want to play with the dimensions of the pictures of visualizations of the categories. play with those presentations. If you want more details give me an email to send you an image that explains you. thanks Thomas.