Hi, very nice forum you got here. At first, sorry if there was topic on this, i don’t know how to write what i’m looking for, so i’l just post a pic 
As you see in attachment below, there is a noise in backgroun, and my mic is not even turned on.
I’m running Audacity on Linux, my mic is some AKG pro wirless, on toshiba satellite laptop. Is there any way to ged rid of that noise? Thank you for answer…
“Noise” in the sense that it’s undesirable, but it’s not sound. You have DC or battery voltage mixed in with what you’re doing. Generally, this happens at the digitizer step – the place where audio voltages get turned into ones and zeros. If that’s your internal sound card, you might consider a new one or even an external USB one.
You can get rid of what you have with Effect > Normalize > Remove DC, but that gets old in a hurry because you have to do that after each recording. You can’t reliably do it post production after you cut a show.
You might consider a new sound card anyway, because if it’s true that nothing’s turned on, that’s also an insane amount of small, wiggly noise, too.
A note: Wireless microphones sometimes deliver a line-level signal. Where did you plug your microphone in? You can’t use the MIC-IN that most laptops have. Read through the Connections part of this even though you’re not on a Windows machine.
http://www.kozco.com/tech/audacity/windowsRecording.html
Koz
I tried mic with jack, no better situation. Mic is connected to laptop via adapter (laptop has 3 jack, i pluged adapter in one where is mic painted on 
). Thank you for the fast answer, it seems i’l have to buy a usb sound card. Any suggestions on low budget usb sound card, i need it only for guitar + vocal.
“Guitar and Vocal” can be quite demanding when it comes to sound “quality”.
You may find some useful suggestions here: Sound Card Reviews
The ART USB pre-amps look and sound pretty good for the price - I don’t have one, but I’ve heard quite a few recording samples that have used a high quality recording microphone with an ART USB pre-amp. I have a UCA202, but that only has “line level” inputs, so not really suitable for you (unless you have a mixing desk).