Please translate your first post, it's not readable.
TCNT is not writeable in normal modes.
But how to get the TIME number?
I don't understand this question. Do you mean how to measure something?
unsigned short t0, t1, tdif;
t0 = TCNT; // get TCNT before something
something();
t1 = TCNT; // get TCNT after something
tdif = t1 - t0 // difference is TCNT ticks spent in something