Usually you can add fog lamps on a car (lower model) where there is provision to add but the manufacturer does not include it in the car.
In that case you can cut out parts of the bumper carefully, insert the exact OEM lamps which should fit perfectly and probably hook them up with your headlights so as to avoid installation of switch on the dashboard.
Or simply your can install a new bumper or a higher version of the same vehicle so you dont even have to do the dirty work.
In your case the Alto 800 does not have provision for fog lamps and that's by design to reduce cost of manufacture and acquiring by the customer.
As you can see on the Alto 800 you dont even have space to add them , manually cutting up holes or replacing the front grill/lights will cost too much and will probably ruin the car.
However there is an Alternative
If you fancy a fog light you can install an aftermarket LED strip on the bumper which will give you better visibility and cool looks , they can work as a DRL also with proper wiring.
Look at the below car which is the Alto's Older sibling and does not have proper holes for fog lamps.
I feel by far this is the Cheapest option you can pursue if you need fog lamps.
You can buy cheap ones on eBAY for around 200 to 500