Looks like a 2.1 to me.

Is that good?

Good? Depends on what you want. It's not a "surround sound" capability. But with good speakers, can still be a rich stereo audio experience.

Val

Do I have to insert the speakers connector at the front of my PC or at the back where my SemaTel Audio is located?

As your installation/setup sheet shows, speakers go in the back. The front connection is normally used for headphones that plug in as needed. The front plug is supposed to turn off the back one, so you don't hear speakers while using headphones.

Val

Will it affect my sound if I connect my headphones at the front of my PC, or at my Integrated SigMa Tel Audio?

You should get the exact same output from the front or the back. The front jack is a convenience to allow easy headphone usage without having to unplug speakers from the back. It's just an extension from the soundchip's output.