How can I make my app send SMS text messages using a user's input?

I am trying to use Twilio in order to send SMS text message confirmations to users who provide their phone number. The only problem is that I don’t have much understanding in regards to WebAPIs. Could anyone please provide some help or guidance in regards to this? I could really use some help.

You already have a post asking the exact same question. Please do not spam.

In the previous post I was asking whether it was possible or not; I am asking for help on this post on how to actually do it now.