Step : 1
1. Go to Configuration > Sales > Payments.

2. Click on edit option "Payu.in" as shown in below attachment of.

3. From left side, select PayU.in settings
4. Select Account type > PayU Money or PayU Enterprise
5. Merchant Key: <Enter Merchant Key> | Salt : <Enter Salt>
6. Click on save button.

Step: 2
1. After executing all the above steps go to Configuration > Sales > Shippings

2. Click on Edit option of the Shippings.

3. Under supported payment methods, select PayU.in and click on save button.
