Un-hooked, make sure your trailer is perfectly level.
Back your truck up to it with the hitch shank/ball inserted into hitch, Back up to the trailer to where you can see the hitch ball and the trailer coupling.
To set up properly the TOP of the ball should be between 1 and 3 inches HIGHER than the top of the coupler.
Not knowing exactly what type/weight/tongue weight of your trailer, and not knowing what type of hitch assemble your using, that about all the info I can give you.
It would help if you indicate what type of hitch your using.....just a straight drop shank or a weight distributing hitch, tongue weight, ect.
When hooked up properly, the front of the trailer should be slightly "nose down" when looking at a side view of the entire rig.
The picture I'm posting shows our rig with our previous Ranger pickup....you can see the nose down attitude.
Dosen't have to be a lot, just enough where your placing weight on the hitch/back of truck. I'll post a pic of the rig hooked up to the Expy later....just getting it set up now.
Pic 1 is the day I picked trailer up at dealer...it was unloaded, about 6000 lbs/575 tongue weight, so not too nose down.
Pic 2 & 3 are just today...first hook up to the Expy for a trial run to set it up. Trailer now at 7000 lbs with a 700 lb tongue weight. You can see the nose down attitude on the trailer....I'm still tweaking it but you get the idea.
Tows beautifully !!!!!
Also...did you mean Casita when you gave the make of your trailer ???? If it is it's probably a very light trailer with a very light tongue weight, Just verify please.