Is it difficult to make iPhone apps?
How do you make an Iphone app?
Google is your best friend for questions like these, but here is a resource to use from Apple themselves. Plenty of reading to be done.
The iOS Developer Library: http://developer.apple.com/library/ios/navigation/#
Specific article for first time app development: http://developer.apple.com/library/ios/#documentation/iPhone/Conceptual/iPhone101/Articles/00_Introduction.html#//apple_ref/doc/uid/TP40007514
If you have no coding knowledge it's going to take a while to get hold and may seem a little difficult at first, but if you stick with it and if you don't expect to be making A grade apps within a couple of hours then you'll get the hang of it.