Quality Center/Test Director is a Test Management tool provided by HP.
OTA is the QC/TD API that can be used very effectively to work with Quality Center ot Test Director.
Below are some simple example usages of OTA.
For more info, refer the OTA doc that comes along with QC/TD.
Searching the support site and sqa forums will also give valuable inputs.
1. Adding a Manual Test case through QTP
The below code can be used to create a manual test case into QC, provided QTP is already connected to QC.
Dim td 'As New TDConnection
Dim dsf 'As DesignStepFactory
Dim tf 'As TestFactory
Dim t 'As Test
Dim ds 'As DesignStep
Set td = QCUtil.TDConnection
Set tf = td.TestFactory
t = tf.AddItem("New Manual test")
Set dsf = t.DesignStepFactory
For i = 1 To 5
Set ds = dsf.AddItem(Null)
ds.Field("DS_STEP_NAME") = "Step " & i
ds.Field("DS_DESCRIPTION") = "The design step description"
ds.Field("DS_EXPECTED") = "The expected"