That grey/white metal top should just twist to relieve the fuel compartment. You probably have to take the glass off first...lift the metal ring up that is holding the glass in place with the spring...you should able to take the glass out now.
See that horizontal gap where the wig adjustment 'bit' is...the top will open up when you twist it so that the 'bit' will slide out of it.
Being new, it all can be quite stiff job to twist...and later on when/if you get bit of rust or soil in between the 'lid' and container...same again, all goes very stiff...
I don't have that exact same model but something similar..and mine opens by twisting action...like opening jar lid.
Once the 'lid is off...the actual burner part with wig should just lift up...or again taken out by untwisting the lot..and you can pour the paraffin in.