Two people is ideal. Push the bike as far up the ramp as you can and grab the front brake, the second person in the bed of the truck grabs the bars and brake from you, walk around to the back of the bike and push the rear wheel up while the person in the bed pushes and controls the bars. Very easy as long as the second person is 1/2 way capable of tying their shoes.
This is how I got my bikes into my 3/4 ton. Damn I love my trailer.
Does the ramp hook at the top?