The sentence structure used is fine.
كيف ظهرت هنا؟
However, the word ظهرت = "appeared", is uncommon.
جئت = "came" would be a more common for of expression.
In The Gulf Area, people would colloquially say كيف جيت هنا or شلون جيت هنا.
in Egypt, the sound of the letter ج would be pronounced as "g" in gate.
it would be جيت هنا ازاي؟
ازاي = "How" in Egyptian.
In Fus-ha Arabic, it would be, كيف أتيت (إلى) هنا؟