how very senior citizens can file their income tax return without physically going to the IT office ?

there are a very large no of income tax payers who prepare their returns all by themselves .The amount of tax is small or it may be even nil in some cases.If it is sent by registered post, the acknowledgement form is not received back.
If it is submitted electronically, there is the question of digital signature,( to subscribe to a digital signature is a costly proposition). In these days of electronics how it can be done in a proper way ?

The answer is to be on the Indian context

When I file income taxes, who can see that I filed?

If I file income taxes, who can see that I filed? Does my employer recieve paperwork?
Ok, the situation is this: I get paid cash. My employer doesn’t want employees who work under the table to file income taxes. So, if I file, will he know?
I’ve filed for the last 3 years. Self employed or something like that. The tax professional used Schedule C I believe. Do they see if you filed under Schedule C?
So, if I file and they get audited but I can prove I got the income through DCF paperwork, do they find out I am the one who filed?
There are 7 employees.. 2 are paid by check.

How to file Income Tax Return ?

Although my Income or Salary is not taxable but still I want to file Income Tax return so that in near future I want to buy a house and for this IT-Return for last 3 years is a compulsion.My question are as follows
1.Can IT-Return be filed Online for Non-taxable Income.
2. What are other process to file tax or show return as a responsible citizen of country