FI Scenario of workflow

Hi experts,

I am new to Workflow. Never created a worflow scenario before.

Ihave the below requiremen. Could you please help me with it.

Creation of a workflow at the time of FI document posting.

Scenario:-

When total value in the document exceeds $1000, then automatically a
payment block ‘T’ should be applied to the vendor Invoice & through the
workflow the information should be sent to all the key users whose ID is
maintained in the authorization group, to approve it for payment .

Once the Invoice is approved then only the payment can be done.

Thanks

Rimjhim