ABAP- Call Tcode itself

Hi experts

I have a program in ABAP with many screens that

one of the screens is my main screen.it means i call other

screens from that screen.

now i want to start this program(or actuly the tcode)

in new session.

suppose my main screen is 0200 and there is other screen 0300

and I assigned tcode zt100 to program.

I want to open zt100 in new session

if user click on one button in screen 0300.

please help me how can do it.

regards ,

Reza Rostami