There isn't really a 4 mirror option. The descriptions in the options are confusing.
If you choose Mirrors = 1, it will result into the cat example on the plugin description.
If you choose Mirrors = 2, it will Mirror your picture 4 times.
Sorry for the confusions, should have named it mode 1 and 2 insted.
Im not sure if this was your problem. If not you probably mean how to use mode 2.
Just create a square image and draw something in the upper left triangle, like in the example and you will understand