Depends on what you want to achieve. For example you can only forward forms‘ input to a mail address and go from there. Or if you use a CMS for example, there a

Depends on what you want to achieve. For example you can only forward forms‘ input to a mail address and go from there. Or if you use a CMS for example, there are lots of plugins which might help you, without getting to deep. Or you can use some "external" services for newsletters and stuff. They offer their own code, JS, PHP and others, you can implement.