Wiki about the mvc
tag might be a good starting point.
The MVC is a theoretical model, a design standard. There is this SitePoint link that can serve as a tutorial for your case in PHP . It's a bit extensive, so I do not know if it's worth posting a whole answer on that.
To improve your knowledge, I think it's also worth going for a better solution in a Framework, like CodeIgniter . Standards and good practices already exist in the Framework and this in particular requires you to write several manual steps.
Another great framework is Laravel .
Both have several questions answered here in SOpt.
On its difficulty in developing solutions, the way is to study, make the examples, learn a three Frameworks, point out the differences on how they solve the problems, and ask here. Bring your questions in a more specific way, putting code ready and asking for more code. There is not much secret.