Currently i am designing database for Portal.
On Portal screen, There are some fields which are having multiselection facility

e.g

1) professional is one of the field having
1)photographer
2)skydiving
3)painter
4)modeling

are values, User can have more then one profession.

Same type of 30 fields are available on single screen.

So the storage for single such field i have to created new table for multiple values storage.
For that total 30 child table get created for a single screen.

Can any one help me, how do i manage this in minimum tables?

All you need is actually just 3 tables:
1) table with the customer information (customerID, name, age, etc)
2)Lookup table for the proffessions (professionId, professionName, etc)
3) table for CustomerProffessions (custommerProffessionId, etc)
Make sure that the CustomerProffessions table has 2 foreign keys: customerID and professionId. That solves your problem nicely, dont you think?

Thanks for reply.

I have 30 different filed like "professional" on single screen. How do i manage in three tables?

Try to understand what "primary-foreign key" relationship is and how to use lookups.