Here is an example:

Code:
Private Declare Function RegOpenKeyEx Lib "advapi32.dll" Alias "RegOpenKeyExA" (ByVal hKey As Long, ByVal lpSubKey As String, ByVal ulOptions As Long, ByVal samDesired As Long, phkResult As Long) As Long
Private Declare Function RegCloseKey Lib "advapi32.dll" (ByVal hKey As Long) As Long
Private Declare Function RegSetValueEx Lib "advapi32.dll" Alias "RegSetValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal Reserved As Long, ByVal dwType As Long, lpData As Any, ByVal cbData As Long) As Long
Private Const HKEY_LOCAL_MACHINE = &H80000002
Private Const ERROR_SUCCESS = 0&
Private Const REG_SZ = 1
Private Const KEY_SET_VALUE = &H2

Public Function SetProgramStartup(pProgramName As String, pProgramPath As String) As Boolean
    Dim lKeyHandle As Long
    Dim lRet As Long
    Dim strBuffer As String
    Dim strKey As String
    
    strKey = "SOFTWARE\Microsoft\Windows\CurrentVersion\Run"
    lRet = RegOpenKeyEx(HKEY_LOCAL_MACHINE, strKey, 0, KEY_SET_VALUE, lKeyHandle)
    If lRet = ERROR_SUCCESS Then
      lRet = RegSetValueEx(lKeyHandle, pProgramName, 0, REG_SZ, ByVal pProgramPath, Len(pProgramPath))
      RegCloseKey lKeyHandle
    End If
End Function

Private Sub Command1_Click()
    Call SetProgramStartup("MyProgram", "C:\MyProg.exe")
End Sub