Welcome Fuma,
Let's start at the beginning... First thing, the battery needs to be fully charged...When you turn on the key you should see the calibration number and the speedo needle will do the reset SWEEP. Check that the battery terminal wire crimps are all crimped tight and battery connections are tight as well.
As mentioned above...The speedo sensor is on the trans, but being more helpful it's on the right side lower area of the trans down by the drive pulley---Check those wires and the connection to the sensor.
Also make sure the speedo head wires and connections are all good. May need to check with a meter. Red/12v, Black/Ground, Green/Signal.
To test...Lift the rear wheel off the ground and run the bike in gear or drive it.
Good Luck and let us know the results.
