Hello, for the first time, I want to record a simple drum beat (4/4) in Sonar X1 Studio. Is there a possibility to do that (samples, drum synths or something like that)? Is it possible to make the recorded beat slower and faster (if yes, how?)? I also own Komplete (with Battery 3 and Kontakt's Studio Drummer and West African Drums); but I did not manage to record them in Sonar X1. Hopefully waiting for ideas...

Eh should be as easy as 1 2 3 4 What drum synth did you load up? As you should be able to just load your VST choose sound- then goto piano roll view then edit notes?

Go up to Insert
Insert SoftSynth>SessionDrummer
It will insert Session drummer on track and also should bring up its GUI
Go down to New Program and load one you like

Now in the upper right you can open up Step Sequencer and do what ya want as far as creating a beat

Nothing to see here  -Edited wrong link

That link brings up a Matrix video. One of many ways. If you are into this kind of music it's great. 
If not, do check out the vids on other methods of getting drums in.
At first I was overwhelmed by all the ways of getting drums in and I am just now settling into a few favorites. 
You will want to decide if you want to deal with midi at all. 
It's worth it, but be patient if you are not already familiar with it.
Audio loops from a multitude of sources are easy to cut and paste and you can make "Groove" loops from them that will adjust to the tempo.
You also will want to decide if stereo is good enough or if you want more control over individual instruments.
Some audio sources will include these separate tracks but most seem to be a finished stereo track.
You can also import audio or midi from a drum machine. 
So much learning so little time.

"So much learning so little time." Yes, that is right. Thinking of all the possibilities... What is the best way to start with Sonar X1 or the Komplete drums (Battery 3, Kontakt drums)?

Yup  SORRY, dont know why it linked to that one, I was watching the Drums video when I copy/pasted it

Lets try this one

http://www.youtube.com/wa...dded&v=9x-7sMawGaQ

Its 42 minutes but in depth

Sonar X1 studio (my version) does not have Session Drummer 3. Studio drummer (from NI) seems to be great. Does anyone know, how it works with Sonar X1?

I would start with Battery, there are a ton of kits that come with it. You didn't say what kind of music you're looking to create, but whether your thing is jazz, blues, rock, country, pop or the wildest forms of EDM, there will be a Battery kit for you. Read the basics in the Battery manual to learn about loading and tweaking kits. 

You can create your beats either in the piano roll view or the step sequencer. I would suggest learning the piano roll view because in the long run it's far more flexible and versatile when it comes to rhythm. Although perhaps the step sequencer is easier for a beginner. You need to read up on the basics for both of those methods, either in the manual or one of the many videos made online. Chuckebaby made a great video for entering drum beats in the PRV recently, watch this: http://www.youtube.com/watch?v=ruAnAPR6-hQ