FM to retrieve help data of a screen field? How to fill structure PHELP?

Hi Experts,

Iam designing dynamic search helps. With connection to this

i have to get the preliminary data about the screen field. i.e the technical details

of F1 help of a particular field. Is there any function module which take input as

screen field name and fetch me its details like domain, database table etc?

How does the structure PHELP be loaded at run time?

Thanks,

Satish.