Hello
As in much snippets you can specify which Tpl you want to use to display what you want.
In the case of FileLister, have a look at
http://rtfm.modx.com/display/ADDON/FileLister.FileLister and at
http://rtfm.modx.com/display/ADDON/FileLister.FileLister.fileTpl
From there it’s pretty easy to understand you have to create a chunk as a mini-template for each part you want to display (file, links for each file displayed etc...), put inside it the HTML code to display your links as you want, and specify the "&fileTpl=`myChunkForFileTpl` &fileLinkTpl=`myChunkForEachLink`" in your call...
Reading the doc is very helpful, at least you’ll find the available properties for the snippets, and what parameters they accept...
Hope this helps
Feel free to ask if you need more explanations
Cheers