You need to use the RAW editing software that came with the Rebel. It sucks though, so I highly recommend getting yourself a copy of C1 LE, which costs $99. If that's too much to spend, you can always download Canon's newest RAW software, Digital Photo Professional, which is indeed far better than the software bundled with the Rebel, but I feel is still far behind C1.
Just to clarify, you don't change the properties of the file. In C1 or DPP, you will edit the raw information in the file thorugh the software, allowing you to change the exposure, color balance, and sharpening. Then you can "export" a jpg, or tiff, to be edited further in other programs, or posted on the web or printed.
Here's a couple of links.
For Digital Photo Professional, go
here, and then click the link for "Softare Applications and Updates" and follow through to get the update for Digital Photo Pro. You'll have to have the other software installed already for it to install.
Info on C1 LE, and a downloadable free trial version, can be found
here.