In order to upload to Rift Logs, you need to install a client application.
The Rift Logs Uploader uses Adobe AIR. You can get Adobe AIR from Adobe's Web Site.
Once you have Adobe AIR installed, you can download the client here.
After installing the client uploader, you must then install the RiftLogger add-on. Although Rift does have a combat log, it doesn't contain enough information for all of Rift Logs' features. This add-on writes out combat log information to the non-combat log file instead.
You can download the RiftLogger add-on from Curse:
Note that the add-on and client uploader are often going to update at the same time, so if you see the client uploader auto-update itself for example, you'll know that you should probably check for a new version of the add-on as well.
You can visit this page for help with setting up the logging process in Rift. If you have any questions about the logging process, you can email us at firstname.lastname@example.org or you can sign up on our forums and post there.