Consider the following methods of programing a microcontroller
Arduino ide- most user-friendly, many tools, quick,  easy
C  - intermediate difficult, need to have more hardware knowledge, more efficient in code handling and storing, more freedom to program.
Assembly lowest level of programing, need to have through understanding of the hardware also, more difficult, highly efficient in code handling and occupies least storage, and allows most freedom to program.

Every pin delivers- 5v max and 40ma current.
Loop- is going to be executed in loop or a cycle.

Use USB to 6 pin ftdi cable to connect to the computer

In the PCB component diagram we see that Tx and Rx are connected to pin0 and pin1 of the attiny. There is a confusion regarding the tx and rx sometimes the pin is are designated tx and rx implying that it goes to rx of the child device and sometimes it implies that tx is the transmitter and rx is the receiver of the parent device.
Initially we tried declaring rxpin as 1 and txpin as 0 as suggested by component diagram shown before, this didnt work for us. It worked on interchanging the rxpin and txpin declarations. This means that they point to the tx ad rx of the child device, we have to match the rx and tx. Here we consider the parent device as the hello ftdi and child device as computer. We will try to send things through this cable to the computer.

Here we programmed the hello fdti to send "print" word to the computer and light up the led when we send letter "c" to the hello fdti.

Code:
#include <SoftwareSerial.h>
 const byte rxPin = 0;
 const byte txPin= 1;
 SoftwareSerial mySerial =  SoftwareSerial(rxPin, txPin);

// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin 13 as an output.
  pinMode(8, OUTPUT);
  pinMode(7,INPUT);
  digitalWrite(7,HIGH);
    // define pin modes for tx, rx:
  pinMode(rxPin, INPUT);
  pinMode(txPin, OUTPUT);
  // set the data rate for the SoftwareSerial port
  mySerial.begin(9600);
}

// the loop function runs over and over again forever
void loop() {

//listen to serial port
if (mySerial.read()=='c'){
  digitalWrite(8,HIGH);
  delay(1000);
  //digitalWrite(8,LOW)
  //delay(1000)
  }
else{}
 
  if (digitalRead(7)){
  digitalWrite(8, LOW);   // turn the LED on (HIGH is the voltage level)
   }
   else {
      digitalWrite(8, HIGH);    // turn the LED off by making the voltage LOW
mySerial.print("print");
   }
 
}
Once you upload this code install gtkterm from ubuntu software center and configure its port to ttyUSB0.

When you press the button on the hello fdti it should print "print" on the gtk terminal.

Now to send from computer side : Open SerialMonitor from the arduino and send "c" to the ttyUSB0. The LED should blink.
 

update 19/11/2015
Making two board communicate with each other
I made a fabduino in week 4. and now going to try to make the fabduino(more info at http://puneethrj.github.io/w4d1.html   and http://puneethrj.github.io/w4d2.html) and helloftdi wih led communicate with each other. As an indication I'm going to use the leds on the boards.
The code in hello ftdi remain the same as above. the following code needs to be uploaded to fabduino. The following code allows the fabduino to light up the led in the helloftdi in same frequency as the led in fabduino blink/ I have built upon the example code of blink from arduino ide for this.

To power the board and communicate I use the power from ftdi cable connected to the fabuino(to program it and after downloading keep it connected) and also the rx and tx from the same ftdi connection. You can either make a temporary solder for this or use jumper wires t o plug it into the holes behinf each terminal in ftdi connector towards the fabduino side.
Match the tx and rx of the helloftdi with fabduino, its not the opposite.
code:
 #include <SoftwareSerial.h>
void setup() {
  // initialize digital pin 13 as an output.
  pinMode(13, OUTPUT);

Serial.begin(9600);
 }

// the loop function runs over and over again forever
void loop() {
  digitalWrite(13, HIGH);   // turn the LED on (HIGH is the voltage level)
Serial.print("c");
  delay(1000);              // wait for a second
  digitalWrite(13, LOW);    // turn the LED off by making the voltage LOWSerial.print("d");
 
  delay(1000);              // wait for a second
}

This program worked and the led on helloftdi blinked in same frequency as the fabduino