First of all we need to know what is this all about.I'm not going to give theory lessons here.
As of now you just need to know that raspberry pi is a single board mini computer(mini in the sense smaller that the traditional computers)
Step 1: Where to Buy
Step 2: What All You Need
1.Raspberry pi (Off course)
2.USB cable (to power up RPi)
3.SD Card (minimum 8 GB class 4)
4.Card reader or adapter whatever you have
5.Ethernet cable (straight through)
And your PC
Step 3: Installing Raspbian With Jessie
In order to install Raspbian first of all download and install following softwares
After downloading, extract Raspbian, you will get an img file
Now Plug in your SD Card
Open win32 disk imager and just write onto your card by selecting Raspbian image
After write successful go to your sd card
You will now see the size of your sd cad has been reduced
Just a new file without any extension named as ssh.(This is to just enable your ssh)
Remember file should not be a .txt file
Now, remove your card and insert it into your Raspberry Pi
Power On your raspberry pi and wait for couple of minutes.
Connect your Raspberry Pi with your PC through Ethernet cable.
After some time open command prompt type " ping raspberrypi.mshome.net "
This will display ipv4 address of RPi
Open Angry IP Scanner Search for alive hosts
You will get two hosts
Copy the ip address of raspberrypi.mshome.net
Open putty paste the ip address and keep the port as same as before
Enter username as "pi"
Now again login as "pi"
Now open VNC Viewer
Type server address as "raspberrypi.mshome.net"
Again insert same user and password
Congratulation you have successfully installed Raspbian.
Now you can explore raspbian os through this VNC Viewer.