Please help, how much quantity of common salt should be taken by a person being on low blood pressure side?

See Below: If you have low blood pressure you should not restrict your salt intake.

1-2g a day: Usually you will find sodium in a large percentage of the foods you eat, so if you are counting right, the average diet should total 1-2 g/kg/day of sodium. If you eat a lot of fast food, the total will be much higher. If you have low BP, you should not worry about too much unless your daily intake is over 3-4 g/kg/day; many dieticians want you to avoid adding table salt to your foods