PlayEpub does support DRM-free epub, Kindle and FB2 files.
If your ebooks are DRM-protected you will have to remove this protection before opening on Playepub. There are several tools you can use to remove protection, I recommend ePUBee or Epub DRM removal.
To read your Kindle books you have to get your book files first and then remove protection as most of them are DRM protected. You can follow this tutorial:
If you have some ebooks in any other format you can try Calibre to convert them to epub. You can also try some online converters: 2epub.com, convertfiles.com.