If you're new to the internet, or really don't know what you're doing, here's some instructions for you:
I do not want you to put my address details into any thing that purports to offer a service! (e.g. greeting cards, amusing websites, freebie offers, websites with “email this page to a friend” features, etc.) Generally, these services exist to collect email addresses to send spam to, or to sell off to others who'll spam them, or even worse.
I do not want to receive junk messages! I don't want to read daily collections of jokes, the latest snippets of news, warnings about viruses, “must see” websites, advertising, business proposals that have nothing to do with my lines of work, etc. I have strong views against marketeering.
I do not want you sending me chain letters! They're illegal, as well as being a complete pain. Not only does this include messages which specifically instruct you to pass them on, but messages that you pass on without direct instructions to do so written in them (e.g. joke collections, ignorant and usually false security warnings, etc.).
Do not forward my emails to other parties with my addresses in them! This is yet another way how spammers get people's addresses to spam them. If you must show someone else's messages to other people, always strip out any addresses from them first.