Hi !
I had a datasheet about this IC . I want to use it as a driver for stepper motors : Does it support both types or just unipolar ?
And , can I use it without IC sockets ???? I don't have one , can I just solder it without a socket ?
thanks !
Does it support both types or just unipolar ?
just unipolar
can I use it without IC sockets
Yes you can but I would advise to use sockets for reuse of the chip and much easier fault finding.
Hmm . Thanks for helping ! I should find a suitable socket 
If you use this one, ULN2803 you can drive 2 steppers
Tack a PCF8574 in front of it and you can use I2C, just 2 pins.
Can someone help me with wiring ? I have datasheets of my IC and I somehow know how to wire it but in the guide it gave +5v from arduino itself .. can I just give power from external power supply then connect the 4 remaining wires to arduino ?
And can someone give me a schematic what shape should I fabricate a pcb and how to connect the 4 remaining steppers to arduino ?
My idea is something like this :
(PAINT)
can I just give power from external power supply then connect the 4 remaining wires to arduino
No.
can someone give me a schematic
http://arduino.cc/en/Reference/StepperUnipolarCircuit
what shape should I fabricate a pcb
I recommend rectangular.
Forget a PCB until you have built one on strip board.