There are various websites for rail ticket booking and booking ticket using these website is not so difficult. One need to register first for booking tickets online. After registration you’ll get a unique ID and password for the login. This is a step by step guide to book rail tickets online.
Go to Irctc.co.in. Click on Signup link.
IRCTC-Signup

Enter your details in the given boxes. Note that one person can make one account only.  More than one registration will lead to deactivation of your previous account.
IRCTC-Registration
After signup, you’ll get unique ID and password. Go to the login page and enter your login credentials and click on the “Login” button.{infokavla.in
irctc-login
Now in the From and To field, enter the name of City you want to travel. Website will automatically suggest you the station code. After selecting the proper station code enter the date by clicking on the calendar icon given at the right. In ticket type select “e-ticket”. If you want to purchase general ticket then Quota will be “General” otherwise in case of Tatkal tickets, select Tatkal from the given dropdown.
irctc-plan-travel
On the right side all the available trains will appear. Click on the dots next to various classes to know the current reservation status and booking options. For example if you want to book 2nd AC ticket in KTK SMPRK K EXP train click on the dot in the 2A column in the Karnataka Sampark Kranti row.
select-class irctc
The detail of that train will appear along with fair summary. If you want to know the status of other class, click on the corresponding dots next to train name and classes.
train-detail-irctc
To book the ticket, click on the Book link given next to the train availability status.
book-train-ticket
Select the original train route by clicking the dots next to “From” and “To”. After that, click on the “Book” button given above.{infokavla.in}
select-train-route
Enter your details (name, age, sex), birth preference, whether senior citizen or not. After filling all the options, click on the Go button given at the bottom.{infokavla.in}
enter-ticket-details
The next page will show you the ticket details. Match all the details and if you’ll find any mistake, go back and fill the form again correctly. Click on the “Make Payment” button to go to the Payment option.
make-payment-railways
Payment option page will open. You can pay via credit card, debit card, net banking, cash cards, EMI options. Select the proper option by clicking on the tab and then choose the name of bank in which your account is present. Proceed to the payment step.
pay-option-indian-rail-ticket
A payment page of that bank will open. Enter the login credentials of your bank to make payments.
That’s it. This way you can make purchase rail ticket online. Railways has recently extended the timings of rail ticket booking. You can book tickets online anytime except between 11:30 pm to 12:30 am. Note that Tatkal tickets are available only from 8:00 am to 8:00 pm.{infokavla.in}