The digital expo guide with all the detailed information will come out 1-2 weeks before the event. In the meantime, take a look at the Princess Weekend Expo Guide--it will be similar. They will re-use the same link URL (which is annoying as you can't go back in time) as the one below.
https://www.rundisneyexpo.run/expo
Absolute basics: You will pickup your bib at the expo, which is at WWoS. The races are staged from Epcot. Bus transportation is provided from every resort to the expo and to the races. You can also drive if you choose, Races start at 5 and buses will start ~2:30.
This may give you a general feel for things, but ask specific questions that you may have.