Allansteff,
Welcome to the user-supported Aperture discussion forum. You should read the [Terms of use|http://discussions.apple.com/help.jspa] that Apple requests we abide by.
How do I make an HDR picture i Aperture
As far as I know, Aperture doesn't support any HDR formats. You can tone-map an HDR image generated from an external program and then import that into Aperture. What I generally do is stack the "component" photos in Aperture. (I stack them so I have all the associated photos together.) Then I use my external program to merge the photos and tone-map them to produce a JPG. I import that JPG and stack it with the component photos, making the new one the stack pick. Then I compare the well-exposed photo with the HDR tone-mapped one to see if I actually did something worthwhile.
I have not used any HDR plugin programs for Aperture, but they exist. I believe they short-cut the export/import process to make it more seamless.
I generally export to a predefined directory and then launch my HDR program manually to work on the component photos in that directory.
[Apple - Aperture - Plug-ins|http://www.apple.com/aperture/resources/plugins.html#editing]
nathan