What is srb2win.exe -opengl and where do i get it

I think i know what to do. 1) You cannot download it 2) go to your SRB2 folder 3) find SRB2win.exe 4) just type -opengl after the srb2win so it should say SRB2win.exe -opengl Got it? I don't know if it will work. You should be in OpenGL mode probably. Maybe correct me if I am wrong. ^^