There is currently only one dedicated parking area for users of the Dubai Tram and that is at the Palm Gateway. The parking area is on level 3 of the building that houses the Palm Monorail.
In order to get to the parking area you need to drive along Al Sufouh Road as if you were driving on to the Palm. At the last minute before you turn right onto the Palm you should stay in the left hand lane and the parking entrance is about 50 yards further on (maybe not even that far). The entrance is still a bit of a building site so you may wonder where you are going but it is signposted so just follow the signs.
Keep going up to level 3 and at one end of that parking area you will find the entrance to the Palm Monorail and the other end is the entrance to the Tram (well at least the walkway).
The Tram end of the car park can be well used so you may not be able to park that close to the Tram entrance if you arrive later in the day.
Once you have parked up you need to follow the walkway that leads out of the car park and across the road to where the tram stops. It is only a couple of minutes walk but there is a short section where you will need to walk outside. There are lifts available for those unable to use the stairs.