correct sentence

The sentence is grammatically correct.

If this refers to use of a personal computer, it might make more sense to state that he should "left-click" on the send button on the screen, as (in North America, at least), there is no "send button" on the keyboard.

Thats one way to write it.

Here is another.

To send text messages, He should push the 'send' button first .

Yes. Some people may differ regarding the use of single or double quotes around the word send, or indeed about the use of quotes at all, but the sentence is perfectly acceptable.

Many thanks to all of you for the response to my query.

presuming the person referred to is God, Jesus or the Holy Ghost - all others have 'he' spelt with a small 'h'.

If God is sending text messages nowadays, I'm bloody glad I haven't got one of those little phones!

If this refers to use of a personal computer, it might make more sense to state that he should "left-click" on the send button on the screen, as (in North America, at least), there is no "send button" on the keyboard.

But in the UK at least, text messages are usually sent by mobile phone (that's "cellphone" to Leftpondians), not by computer.

I believe that if God sent a text message, you wouldn't need a phone or a blackberry . . . i suspect we're talking gigantic, blazing letters in the sky.