Attachments are new in ArcGIS 10. Attachments allow you to add files to individual features and can be images, PDFs, text documents, or any other type of file.
Attachments are similar to hyperlinks but multiple files can be associated with a feature, but attached files are stored in the geodatabase, and files can be accessed in several different ways. Through HTML pop-ups, the attachments can also be opened in Web applications, ArcGIS Explorer, or ArcReader. Attachments are stored inside the geodatabase, you can share a geodatabase or make a layer or map package and all the attached files are included with the data automatically.
Download link below is pdf tutorial how to to enable attachments on the feature class, adding attachments to features and viewing attachments. This tutorial only available in Bahasa Indonesia.
Download mini tutorial using attachments in ArcGIS 10 here