want to write to a file on sd at a specific location ...

hello my friends , i have a 264 bytes file on sd card
i want to write only counting from the first Byte 0

Count up through all the bytes until i reach the Bytes
35, 36, 37, and 38

then i want to change the hex values at 35, 36, 37, and 38

how can i do this?

( also if it helps the offset i want to change is 0000001D at this location 0x23 0x24 0x25 0x26 )

i have this code , but i do no know how to go to the places 0x23 0x24 0x25 0x26 ...
and write hex values to them...

long offset = 0x0000001D; // Define where to go to
File myFile = SD.open("1.txt");
if(myFIle)
{
if(myFile.seek(offset))
{
// Got to the desired location
}
myFile.close();
}

ups , its simple.... just go to the offset and replace the hex value
for example at offset 0x0000001D at the location 0x23 means 0x00000023

long offset = 0x00000023 // offset-i-want-to-modify
File myFile = SD.open("1.txt");

if(myFIle)
{
if(myFile.seek(offset))
{
// Got to the desired location
// write to it ....
}
myFile.close();
}