Hi ,

So along with the application form candidates need to pay an application fees . It is :

General/OBC of Karnataka- Rs. 650/-

SC / ST of Karnataka- Rs.500/-

The step by step process include filling candidates' details, study information,  postal address , declaration and then comes the payment of application fees using net banking or credit/debit card. 

So if the option is not available it might mean there is some error in the portions you have filled and without rectifying it you cannot move to the payment option . 

For detailed information check this link. 

https://www.careers360.com/exams/karnataka-pgcet

Hope this was helpful. 

For further queries please approach careers360.