Hi all, i'm new in this forum 
I think my question is clear, i wanna run a 12V motor using an arduino Uno !
How to control the speed and the direction of the motor !
Thanks a lot
You imply that you want to be able to drive it in both directions, in which case you need an H-bridge motor driver circuit. You can get motor driver shields that provide these (typically in pairs), you can also get them as standalone boards, you can even get Arduino clones with integrated H-bridge drivers. Whichever type you go for, the driver circuit would need to be rated to suit the voltage and current used by the motor - I would recommend giving the driver and power supply at least a 50% spare capacity since it is not a good idea to run these things right at their rated limit.
Thank you Peter for your reply
I will buy an H-bridge, but can you give me the reference of it ? which one i ll need ?
I am building an H-bridge, but i don't have diodes. Can I instead use LEDs?