Can anyone tell me step by step steps to connect guitar rig 5 to Mustang 1 amp? So that the sound comes out of amp, not compter speaker

You'll have better luck just playing Guitar Rig thru your computer speakers (assuming you have decent ones of course) GR is supposed to eliminate the need for an amp and allow you to record at home or even play thru your laptop thru a PA. I am just gonna throw it out there and guess that you found out that it really isn't "all that". Assuming that you don't have good speakers, and you are just trying to see how it sounds coming out of your amp, you'll need to go to Radio Shack and find an 1/8" to 1/8" mini jack (they cost 10 to 15 bucks) and plug the computer's output into the little stereo input on the MI ....that little input that is for plugging in your mp3 player so you can play along with whatever songs you want.