You can use following vb code.
Visual basic code to create Outlook task with reminder.
Hope so it may help you out.
Dim appOutLook As Outlook.Application
Dim taskOutLook As Outlook.TaskItem
Set appOutLook = CreateObject("Outlook.Application")
Set taskOutLook = appOutLook.CreateItem(olTaskItem)
.Subject = "This is the subject of my task"
.Body = "This is the body of my task."
.ReminderSet = True
.ReminderTime = DateAdd("n", 2, Now) ' Set to remind us 2
' minutes from now.
.DueDate = DateAdd("n", 5, Now) ' Set the due date to
' 5 minutes from now.
.ReminderPlaySound = True
'add the path to a .wav file on your computer.
.ReminderSoundFile = "C:\Win95\media\ding.wav"