Command tasks: Get across an obstacle without touching the shark infested custard as a team (or somesuch)
Grenade Test: You will have a lesson about the hand grenade which you will be tested on later - judges your retention abilities.
Practical grenade test: Crawl through course and throw (practice) grenade at target.
BARB Test: Computer test which, somehow, judges your brain power (or lack thereof)
Physical: 1.5 mile run, jerrycan carry and some static weight lifts - IIRC the run is the only pass/fail element of these under 14 minutes and you're fine but it is personal best so give it your all, it's only 1.5 miles.
Ice breaker: 3 minute talk about yourself, your personal life, motivation for joining TA, strengths. Judges your confidence and ability to communicate.
There will be a couple of lectures about the TA history and pay etc but nothing overly taxing.
Remember you are being judged all the time - give it 100% it really isn't difficult.