If you have the top laid out right, the spray tack and brush on adhesive on right, the material has enough bulk that all you really have to do is smooth it out with the palm of your hand. Very little force and it'll lay down smooth to start with. Around the drip edge you'll have to "fold" a bit with your fingers, but again, if the top is made right it'll lay right in.
As mentioned above, it's really not a big deal to do it yourself. There's no magic to it. Just a bit of patience and some common sense.