ruben23
You should read BOTH Manuals.
Read them slowly and read them twice each, ie in order to comprehend the wealth of information contained in them.
Please note that a mail server is configured by default when you do a normal standard installation of SME Server, either in gateway server mode or server only mode.
Please also click on the Wiki link at the top of the forums, as this provides information about the SME features and standard configuration.
Please also read this page as it will provide you with a lot of beginners guidance
http://wiki.contribs.org/SME_Server:AdviceAlso read the FAQ for useful additional specific tips, again linked at top of forums.
Some words of advice for you. Please learn to be proactive in response to answers & suggestions given in these forums. You could have easily looked through and read both manuals yourself. They contain all the step by step instructions to setup all aspects of SME Server, and had you made an effort to read them, you would have discovered that.
Same goes for the Wiki and other pages, all linked at the top of these forums.