use "more" option / change font size / photos in widget

Hi, three questions don't find any answers for me. 1- I don't find how to use the option "more". In the chapitre modify page I see the button, but I don't understand how I can use it. (step by step), 2- I try to change font size (preformated smaller, title bigger), but I don't now how to use Custom CSS box, 3- Is it possible to insert picture in widget ? (do you need my website ? http://jardindeshetres.fr/) Please excuse my english, it is very bad... Thank you very much,