How do I insert an image into a pdf file?
That really depends on how you create the PDF file. If you create it with MS word for instance, you just add the image to the word document.
If you are programmatically creating a PDF file, you create an XObject of subtype Image and refer to it in a Do
command within a page stream. See section 4.8 of the PDF spec for a lot more details.
I have a couple different answers for you; depending on your situation.
If you are creating a PDF from a program/filetype such as Word, HTML, etc. You'll need to consult the help documentation for that program. Typically, programs will use some sort of variation of "Insert, Image, From File..."
If you already have the PDF and you're using Adobe Acrobat Professional (I will just describe version 8, as it's the version I have installed), you can use the left side-bar and find the Attachments icon (looks like a paperclip). From there it should be fairly straightforward: click the Add Attachment... button and you're off.
Hope this helps.