Rachidk said
Thank you Mandrake. You mean a fill flash?
 

Yes, I would start with the fill flash mode using the flash that's built into your camera.
The flash will allow you much smaller apertures (greater Dof) and a faster shutter speed to better freeze the action.
I've found a short video (although referencing the D3000) which may be of help.

Mandrake said
With quickly moving people and shot indoors it may well be that flash is your best bet.
Otherwise... with these, I might try increasing the ISO to 800 or even 1600 to see what your camera can handle.
You have the aperture very wide which greatly limits depth of field putting most of the image out of focus.
To get higher shutter speeds and higher aperture setting you would really have to increase the ISO.

Thank you Mandrake. You mean a fill flash?

Rachid

easyexposure said
Interesting! What are they doing? 

I can't see your exposure settings, but I am guessing that your shutter speed was a bit too slow, which caused the loss of sharpness. 

Sorry for the late reply. The EXIFs are:

F/1.8 - 1/160 sec - ISO-400

F/2 - 1/125 sec - ISO-400

It was my first try on moving objects(people). In fact they were dancing and constantly moving. I wanted to try without flash. I am playing (learning) with my Nikon D3200 in different situation .

Rachid

I can't see your exposure settings, but I am guessing that your shutter speed was a bit too slow, which caused the loss of sharpness. 

Rachid