Stick your rear tyre into those slats, usually this allows locking frame and rear wheel. Wirelock on the frontwheel if wanted.
Also, the foldable locks are much more practical than the U-style locks.
I'm pretty loyal to the U-lock, it's the fastest. When I was a messenger, locking and unlocking 50 times a day, we all used them. It takes 5 seconds when you got your system down.