Procedure that does encryption I am looking for an algorithm/procedure that encrypts a text
where the alphanumeric data is encrypted into password-protected alphanumeric data.

I have seen other algorithms where a text like "Hello, How are you?" will be encrypted into something like this: JHo+8D337H/hLwg9n2n2n8+du783bsH9hdsSEWj93==

This is not what I am after.

I am looking for something that does this: "Hello, How are you?" 
will be encrypted into "Kjehh, Jey uwh wmd?"

Any idea how to do that?
I would suggest using a classical cipher like Vigenère, for example:

Plaintext:  Hello, How are you?
Key:        topsecret
Ciphertext: Asads, Jfa tks ngy?


But bear in mind that classical encryption techniques are very insecure by modern standards.