You need to get the free MIME and SMTP classes which are available on the Wrox web-site (www.wrox.com), there is documentation there and the MIME part takes as many different parts as you want including attachments like graphics or document files and returns a Base64 encoded result.
You then pass this to the SMTP class and it sends the message.
Full documentation is available within the zip file that you can download.
I started to write my own classes to do this but gave up because it was one of those tasks where someone had been there before and it works and is reliable and easy to use.
Don't waste time trying to re-invent the wheel with mail as it's not the easiest thing to do.
Hope this helps
James