Hello,
I switched to Linux a few days ago and I was looking for some good drawing software- I found Krita and I must say it's great! But there are a few things that I can't figure out.

First, how to use patterns. Is it possible to draw with the brush with selected pattern? I tried everything and I just can't do it.
Second, any tips on how to draw speech bubbles? I tried with drawing ellipse of course, but the lines are to thick for a speech bubble. I can make it thin on the vector layer, but then I can't "edit" it (add a little "tail" at the end to show who is talking, if you know what I mean).
Third, how can I move selected object?

To draw with a pattern go to "source" inside the brush setting and then select pattern.

In case you want to make a vector speech bubble, one way would be to convert the ellipse to a path and then edit it. Select the ellipse and double click, then click on "convert to path" in the tool options. Once that is done you can insert new pointer and move the outline.

Click and then drag the object, just click in other applications. Make sure that you are in the shape handling tool (with the cursor).

Thank you, I got it now, though I think it would be nice to have a speech bubbles as an option

I have another question/problem. It will be hard for me to explain, but I'll try
Let's say I draw some object on one layer and then create a new one, is it possible to draw on the second layer but only on the field where the object on the previous layer is? I know photoshop has this option, but I don't know how is it called. Like in this video on 19:15:
http://youtu.be/9kQllLy_X4I?t=19m15s

I also can't seems to find a "magic wand" tool for selecting an area with a certain colour?

While you have a selection active you can paint in any layer without spilling outside the selected area.

To select by color you have two options:

The first one selects the same color in the whole layer, the second selects a contiguous area of color. In the "tool options" tab set "fuzziness" to 5 or less, otherwise you end up selecting half of the canvas.

Once you have your nice selection you can right click over any layer an save it with "Local selection". The saved selection can be turned on/off by clicking the circle, i.e. only horns selection active:

Thank you so much!

You're welcome!

I forgot to add that you can hide/show the selection border with ctrl+H.