How to read the value of a text box from web server and return with href??

Hi, I have an arduino with a website in which I have a text box and a button. The idea is simple: when I click on the button I want to read the value of the box and return it with href. Does anyone know how to do it?

In HTTP you can have 2 methods of getting form values from client: GET and POST which you specify in form tag.
GET passes form values in the URL string like you see the url of this thread here has ?topic=429195.0 which means exactly what it looks like, and the ? marks the start of the variables while multiple variables are separated with & like ?a=1&b=2. So all you need is just catch the URL and parse it.
With POST form data are passed with HTTP request headers. Not going into details it was explained for example in this thread:

ok, I understand. ThankĀ“s. But how can I read the value of a text box?

You need to lean about web programming...

There are multiple options, forms, GET and POST etc...

Basically you need "some code" that will read the text box value, build up a URL and send that back to the server. The server decodes the HTTP request extracts the value and deals with it.