Most web-editor programs have an option for inserting your email as a link - if you're editing the HTML yourself then the code looks like this:
One thing you need to worry about - these days spammers have programs that search the web for "mailto" links like the one above. Almost all the spam I get comes from such spam "spiders". So if you put your personal email addresses on the website, the spammers will soon get hold of it and start sending you stuff on it. The best idea is to make a special email address (perhaps at somewhere like hotmail or yahoo mail) and use it for the website's mailto links. When the spammers find it, make a new account, alter the website accordingly, and abandon the old one.
<a href="mailto:firstname.lastname@example.org">email us</a>