Pass value between different form user search field value f

i am developing windows application in C#.

my requirement is in First form i have multiple textbox like name,id,patient etc.. if i search by id, name and patient information will show in form1, or if i search by name, id and patient information will show. it is working in my first form.. now i have second form where there is only one textbox, which should suppose to show the value i entered to search in first form. (i.e suppose i search information using id. then id should show in second form textbox. or if i search information using name. then name should show in second form textbox.)

Please Help! i am searching it for past 3 days but not getting how to do.

Thank You.