Following code is to enable PORTB as output and set it high.
A pullup resistor will be required at input PORTB2.
# include <avr/io.h>
int main (void)
{
DDRB = 0xFF;// set all pins on PORTB for output
while (1)
{
PORTB |= (1<<PB1); // set Port PB1 high
}
return 0;
}