I am interesting to know if I would like to create a website which contains a feature of sending/receiving text message to/from users' cellular phone. Could any one give me some instruction how to complete this task from scratch.

Does any software or web host company provide developing support?

You need toi subscribe to a text relay service, this will cost money. They may give you a guide, or even offer you software for this.

It already exists... When you go to your service providers home page they have a section were you can send a text message to anyone.