Paypal Paynow Button Integration Issue

[suppliedteacher]

Hi Team,

I am using paypal paynow button and the transaction shows successful. But I am not getting any guide about how to get the transaction id and other details after a successful or failed payment. Can you please suggest? I also need to know about how to automatically return to the merchant without clicking the return to the merchant button. 

Thanks 

[suppliedteacher]

I am using php