Look into how the DesktopRAPIInvoker application transfers files between the desktop and the CE-side device.
Latest Files Articles
Create powerful, panoramic CE file handling capabilities from the desktop side using RAPI.
Explore the techniques for allowing the user to find and access files in WinCE using the Common File dialog.
[Update] WinCE did not implement the CStdioFile text file functions. Check out this article if you need to read and write text files on CE.
CCeFileFind - File Finder class for Windows CE
Latest CodeGuru Developer Columns
In this installment of the Xamarin series, learn about Xamarin.Forms.
Many people are still using older programming languages. Think about the pros and cons.