Hello and Welcome to LinuxQuestions,
Here you go for Postfix: Postfix configuration
And this one for Apache: Apache configuration
Those are 'from the source' and complete. So you can start reading and learning. Don't ask LQ users to provide step by step guides or howtos. Those can be found using Google or another search engine. You turn to LQ when you have problems or questions that are more specific and that you might encounter when following a guide. Have fun with Linux.