Already made it so you can switch pages with the dpad if enabled in the settings.
Finally tried the app, the manga reader doesn't work for me; i get can't open .jpg errors
It's saying it failed to load the first page, right? Make sure you're doing the following...
Pointless zeros. If your first page is called 01.jpg, pointless zeros would be set to 1. If your fist page is 002.jpg, pointless zeros should be set to two. Get it?
File extension. Just make sure that you set it to .jpg. And make sure your files aren't something like .JPG.
Prefix. Pretty much, something before your file name. If your first page is called HappyStory01.jpg, prefix would be HappyStory. qqwerty-01.jpg for the first page would have "qqwerty-" as the prefix.
Selecting the right thing. When you select a manga to load, you should be selecting a folder name. Your images should be in a folder. Like /Manga/Naruto/1.jpg. When selecting the Manga though, you would select "Naruto" (For that example I gave) rather than an image name. Like 1.jpg.
Image Resrictions. Images can only be so big. If your first page is huge, like 2500x2500, then you need to shrink them. Use Fotosizer to shrink a lot of images at once. Try using a smaller image and see if it works. If it does, your problem is with the image size.
If you still need more help, ask.