you will need 3 things.
1. A camera that will play the tapes
2. A Digital Bridge to convert the Analog tapes to Digital
3. An iMac with iMovie.
Given that you have #1 and #3, you are left with trying to find #2.
Dazzle made one but no longer produce for the Mac but, they are still available:
See this link: http://www.amazon.com/Dazzle-Hollywood-Firewire-Digital-analog-Converter/dp/B00006BC2H
However, if your camera has a Firewire connection, also known as iLink, you will not need the convertor. Just plug the camera into the iMac, launch iMovie and suck that video in.
Once done, edit in iMovie and Share with iDVD to make a DVD.
what is the easiest and best software to transfer Hi8 tapes to my computer