You need to write a transformation and use one of the methods which work with the attachments. Sample transformation from the sample corporate site:
- text transformation macro: {% GetImage(NewsTeaser, title, 90, 0, 0)%} where NewsTeaser is the attachment field
- ASCX transformation sample, different one: <%# GetAttachmentIcon("AttachmentGUID") %><a target="_blank" href="<%# GetAbsoluteUrl(GetAttachmentUrl(Eval("AttachmentName"), Eval("NodeAliasPath")), EvalInteger("AttachmentSiteID")) %>"><%# Eval("AttachmentName",true) %>
Just to list different methods...