Using Secondary weapons and Grenades?

[sandsnake]

Alright, I apologize in advance if this is somewhere else. I searched and read and searched and read, but no love.

How do you:
A> Use grenades? 
B> Switch to secondary weapons?

I've tried everything from random buttons to right clicking every relevant seeming spot on the screen and I'm getting no luck.

Thanks!

[Mattn]

you have to put the weapons into your hands (either before you enter the mission, or via inventory menu when you are in the mission already (key i))

then you can click the shoot button on the hud and you will get a list of fire modes. that's all - for almost every weapon