Hello and welcome to the forum,
TURN OFF THE CAPS. . . That is just rude. . .
From the little you've posted, suggest you read the file and store the maximum and minimum salary values as they are discovered. While discovering the min and max, sum all of the salary values read and count the records read. When end of file is reached show the min and max, divide the total salary by the number of records to get the average and show that value.
Hope this helps,