If you own the material, you can use various methods to transfer that info to roll20 for your games. If these are hard copy modules, books, etc. you'll probably have to scan them and import as images. Maybe use an OCR process for text... If these are in an electronic format(pdf), you'll probably want to come up with a conversion method ( pdf2jpg or similar). Depending on the format and your pdf reader/editor, you may be able to copy/paste or screen cap and crop into Roll20. Roll20 only imports pdf's one page at a time. ;-( Hope this helps. Cheers