how do i make it that high graphic way?
how do i change the mod in my multi player room?

To get higher graphics, known as shaders. You go to Setup/Options, anc click on the 'Shader' box. If the graphics dont improve, your graphics card on your computer cannot handle the shaders.

Yo change a mod in multiplayer, tpye /set mod modname.tbm

Or, press the Escape Button, go Setup/Mods/ and pick your mod

Well, you can only change the mod in multiplayer if you have an @ in front of your name, which means you're a server admin.