How to go to the System Prompt in SAP

Hi,

i am a beginner in SAP.

I need to run the lgtst test from my R/3 server

system prompt:

lgtst -H /H/<saprouter ip>/S/sapdp99/H/<sapserv ip>/S/sapdp99/H/oss001/S/sapmsO01 -S x -W 30000

I am not aware how do i go to the system prompt.

I only know the SAP Easy Access screen on the SP GUI where i we can run transactions.