While Experios allows you to build forms into your publications, until you set up some way for submissions to be processed, they will remain non-functional.
Essentially, this means that you have to provide a destination to which data will be sent when a user submits the form. This will typically take the form of a script that is hosted on your own hosting environment. This script will collect the information entered in the form and, for example, send it to an email address, or save it to a database.
You can specify the location of your form-processing script by entering the url of the script in the Action field of your form Properties. You will also have to specify whether the form should submit data using the GET or POST method.
There are an abundance of free boilerplate scripts available online which can be used for processing basic form information. However, setting this up is a task best handled by a developer, as poorly-handled data can leave your destination server vulnerable to security exploits.