How to connect a PS3 controller to steam?

i dont think the PS3 controller has PC support, but a wired (not the wireless with wire adapter) Xbox360 controller works with windows

I use MotioninJoy to emulate an XBOX controller for most games

I'm not sure if this works with the official PS3 controller but you might want to look here. I'm using cheap unofficial PS2 controller(Hama Black Force) and I had no problem using this tutorial and x360ce.

The PS3 controller is a Generic USB Joystick Device, so yes it is supported. The configuration would depend upon the individual game.

EDIT: I missed the Big Picture Mode part. I haven't made use of it because I enjoy my PC with a mouse and keyboard. It shouldn't take much effort to find the answer though.

Download the DS3 tool and install the drivers with it, it is a controllet emulator that support PS3 controller. Also when using it remember to emulate a xbox controller and not the ps3 since many games does not support it.

I use a PS3 controller to play my steam games.Download Motionjoy(aka ds3 tools) and emulate the ps3 controller for xbox.If you want to connect it without usb you will have to install some BT drivers.

i use motioninjoy

i use xpadder

I use DS3Tool/MotionJoy.
Works really well.

DS3 tool motionjoy is what I use, then make it act as an xbox controller or map the keys yourself :)
you can bind it to a bluetooth dongle or to your bluetooth in your pc (if you have any)
or use the cable ofcourse :)
good luck and happy gaming!