Simple Programming Issue - Need Help

I'm not the expert programmer as a lot of you are and am taking a few courses to learn more.  Anyway I've been working on a program to control two stepper motors using micros instead of delay and have a problem I can't solve. The program will run the stepper motors but as soon as I add to the program to run the motors forward and reverse, all that happens is the motors run in reverse. I've tried this same programming using the example of Blink Without Delay by modifying the program to blink slow than fast. All it does is blink slow. What am I missing?

Chuck

*/

// constants won't change. Used here to set a pin number :
const int ledPin = 13; // the number of the LED pin

// Variables will change :
int ledState = LOW; // ledState used to set the LED

// Generally, you should use "unsigned long" for variables that hold time
// The value will quickly become too large for an int to store
unsigned long previousMillis = 0; // will store last time LED was updated

// constants won't change :
const long interval = 1000; // interval at which to blink (milliseconds)
const long intervalFaster = 500;
void setup() {
// set the digital pin as output:
pinMode(ledPin, OUTPUT);
}

void loop() {

unsigned long currentMillis = millis();
for(int x = 0; x<=4; x++)
{
if (currentMillis - previousMillis >= interval) {
// save the last time you blinked the LED
previousMillis = currentMillis;

// if the LED is off turn it on and vice-versa:
if (ledState == LOW) {
ledState = HIGH;
} else {
ledState = LOW;
}

// set the LED with the ledState of the variable:
digitalWrite(ledPin, ledState);
}
}

//Blink Faster
for(int x = 0; x<=4; x++)
{
if (currentMillis - previousMillis >= intervalFaster) {
// save the last time you blinked the LED
previousMillis = currentMillis;

// if the LED is off turn it on and vice-versa:
if (ledState == LOW) {
ledState = HIGH;
} else {
ledState = LOW;
}

// set the LED with the ledState of the variable:
digitalWrite(ledPin, ledState);
}
}
}