When to activate and deacticate Chip selects

I am using 6164 external RAM. To write data to memory i need to bring /CE1 and /WE(active low) low and to read data from i need to enable /CE1 and /OE (active low). I want to know where do i need place the read and write functions in my source code. I am placing my source code which write variables to external RAM and makes port pin 3.0 high and low after a delay of 1s.this program has not been compiled. just tell me where to place the chip select functions in the code.

#include "absacc.h" // header file acessing external RAM{xbyte/xdata)
#include<reg52.h>

#define i_variable XBYTE[0xA00A]

sbit test_pin=P1^0;
sbit write_pin=P3^6;
sbit read_pin=P3^7;
sbit clock_pin=P3^5;
sbit RX_pin=P3^0;
sbit TX_pin=P3^1;

void high_low(void);
void port_init(void);
void delay_1ms(void);
void delay_9ms(void);
void enable_external_ram(void);
void main(void)
{ test_pin=0;
while (1)
{ high_low();
} }

void high_low(void)
{ xdata int i; //data is written at address 0xA002 i=i_variable; // The variable i is stored at the location at specified by XBYTE test_pin=1; for (i=0;i<=100;i++) { delay_1ms(); delay_9ms(); } test_pin=0; for (i=0;i<=100;i++) { delay_1ms(); delay_9ms(); }
}

void read_external_ram(void)
{ //This function reads the external RAM memory. To read the external Ram memory the /CS5
// and /OE pin need to be enabled.
//The write pin is inactive when the read operation is performed.
P2=0x00;
read_pin=0; //Enable A13, A14,A15 to de-select /CS5 //which is chip select to 6164 EX RAM
}

void write_external_ram(void)
{ //This function writes to external RAM memory. To write the external Ram memory the /CS5
// and /OE pin need to be disabled.
//The read pin is inactive when the read operation is performed.
P2=0x00; //setting port0 as output
P2=0x05; //set A13, A14,A15 to select /CS5 which is addressed to 6164 EX RAM
write_pin=1; //active low for 6164 input for 6164 is 0
}

void delay_1ms(void)
{ // Configure Timer 0 as a 16-bit timer
TMOD &= 0xF0; // Clear all T0 bits (T1 left unchanged)
TMOD |= 0x01; // Set required T0 bits (T1 left unchanged)
ET0 = 0; // No interupts
// Values for 1 ms delay
TH0 = 0xF8; // Timer 0 initial value (High Byte)
TL0 = 0x2F; // Timer 0 initial value (Low Byte)
TF0 = 0; // Clear overflow flag
TR0 = 1; // Start timer 0
while (TF0 == 0); // Loop until Timer 0 overflows (TF0 == 1)
TR0 = 0; // Stop Timer 0
} void delay_9ms(void)
{ // Configure Timer 0 as a 16-bit timer
TMOD &= 0xF0; // Clear all T0 bits (T1 left unchanged)
TMOD |= 0x01; // Set required T0 bits (T1 left unchanged)
ET0 = 0; // No interupts
// Values for 9ms delay
TH0 = 0xB9; // Timer 0 initial value (High Byte)
TL0 = 0xAF; // Timer 0 initial value (Low Byte)
TF0 = 0; // Clear overflow flag
TR0 = 1; // Start timer 0
while (TF0 == 0); // Loop until Timer 0 overflows (TF0 == 1)
TR0 = 0; // Stop Timer 0
}