If you want to convert the 0-1023 range returned by analogRead() to a different range then take a look at the map() function. For some target ranges there are easier ways to do it.
For instance
int value = analogRead(A7);
value = map(value, 0, 1023, 0, 255); //convert range to 0 to 255
is equivalent to
int value = analogRead(A7);
value = value / 4; //convert range to 0 to 255
which is equivalent to
int value = analogRead(A7);
value = value >> 2; //convert range to 0 to 255