WinCE API を介した eVB File Access を確認してください。記事のサンプル コード (コモン ダイアログからファイル名 (myFileName) を既に取得していると仮定します):
Public Const GENERIC_READ As Int32 = &H80000000
Public Const OPEN_EXISTING As Int32 = 3
' CreateFile will open a file handle (hFile) to the file in the myFileName variable
hFile = CreateFile(myFileName, GENERIC_READ, 0, 0, OPEN_EXISTING, 0, 0)
lFileSize = GetFileSize(hFile, 0)
' String(lFileSize, 0) will prepare the sContents string variable
' to hold the contents of the file
sContents = String(lFileSize, 0)
' ReadFile actually reads the file we opened earlier and puts the contents
' into the sContents variable
ReadFile hFile, sContents, lFileSize, dwRead, 0
' Put the contents we read into the textbox
myTextBox.Text = sContents