If you really want to tackle this job, you can probably do it. First buy a factory manual, not clymers. Clymers is ok for some tune up stuff, but is not detailed, so don't waste your money.
You may wind up with more hours doing it yourself, than it is worth, instead of buying a rebuilt one on line.
Then go to: http://shop2.evinrude.com/Index.aspx?s1=b4h7ie7g1rufebuueg0puhf2u3&catalog_id=0&siteid=1
this is the omc parts website. they have parts diagrams and parts list below it.
you will need to have the model #, year, etc.
Once you have the right part numbers for the parts you need, go to marineengine.com ( I like this one best, they have a lot of my money) or iboats.com
at the top right on marineengine.com, enter part number and it will give you OEM parts if available, and after market parts.
it will not tell or show you how to do it though.
If you plan to work on your own motor, the manual is awesome. It will show you how to change your spark plugs and which ones to use for your motor, all the way up to completely rebuild your entire motor with it. But you will need some special tools for some applications. car tools usually won't work.
You can look online for rebuilt lowers. I think I heard about a place in Florida that is very good, cheap, and will ship to you. $750 and up I think? Depends on the size lower.