Configuration of workflow

Hi Friends,

I got a requirement to configure a workflow for PO creation with following condition:

  1. if total amount is greater than 1000 USD

  2. Then it has to be approved by a particular user Mr. X

  3. Mr. X must get notification that workflow is assigned to him

for this purpose i am using > procuremnet module > workflow > Purchase order workflow >

BUt how to add these condition ?

please help.