HI Meena,
Instead of F4 help, why you cannot go for making the field as hyperlink.
To make the field as Hyperlink- You cand do the following changes:-
In the element list, for the field you just now created (TEXT) , click on properties , and for Hyperlink click the Attributes
In the PAI, for the SY-UCOMM as 'TEXT' - you can use the abap statement "Cal Transaction" to meet your requirement.
Thanks,
Gupta