1. you need to gather a list of emails. Lets assume that you have right now. There are few of email marketing tool out there, one that I tried they give you 60 free trial with plenty of templates to choose from. Do a quick search and you will find lots of them, I would suggest you to try a few first.
1. Have you got a list? If you haven't then you need to consider buying one or building the list (a long process but worth it) 2. You'll need to actually write the emails. I write my own, but then I'm a content writer. You can hire a decent writer to do this from the DP content forum. 3. You should also get software to track responses and minimise spam blacklist problems. It depends on the scale. For small timers like me Constant Contact does well (if you're building a list then aweber also has its ardent fans). If you want to get more serious than that then PM me and I'll point you to a forum.