Lotro-wiki has a decent guide for Legendary Items here.
Have a look through that and check out some of the pages linked from that one for more information on any aspect you don't understand.
If you're still unsure about anything then come back here and ask about it, someone will always be happy to answer.
[center][url=http://forums.lotro.com/showthread.php?18699-How-to-get-help-on-the-Tech-Forums-and-how-to-contact-Turbine][color=gold]How to get help on the Tech Forums and how to contact Turbine[/color][/url]
[color=green]Please reply to the topic or PM me if a solution I posted works for you: The more data I can gather the better I can help.[/color][/center]