Trestle tables are really not that hard to set up. The only thing you really need is a 1/2 inch deep socket ratchet. Something else that may prove useful is a 3 or 4 foot long level. To get your table nice and level.
Ok here is the gist of it.

Unwrap the end supports and the spreader bars. The smaller bar goes up top, though this varies with the model of your table.
As you'll see in the video it's easier to lean the end support after you have inserted the bolt into the hole. Place a washer over the bolt hand tighten the nut and then cinch it all down.
Make sure just to get it tight as over tightening can begin to back the bolt out.
Repeat those steps for the lower spreader bar.
Switch sides and slide the bolts through the holes, add washers & tighten the bolts.
Once the base is together this is the time you want to level the table out. So check it both side to side and length wise adjusting the levelers in the feet as necessary.
Once level you'll need 2 people to put the table top on. If your table was ordered with leaves you'll want to open the table all the way up. walk it over the base, you'll have to rely on each other to get the bolts through the holes. IT takes a minute and good communication skills but you can easily do it.
If you have a solid top table you'll need to get it close and then get under the table to lift & guide it on to the bolts.
If done properly it can take as little as 6 minutes to set up.