Only 'gde' is an accepted transliteration for "где". I recommend using Cyrillic to type instead as it can be frustrating to try guess the "correct" transliteration and being able to read in actual Russian will be more beneficial for you in the long run :)
Because "я" (ya) is "I" and "моя" (moya) is 'my' for feminine singular things. They are different words. The original Russian sentence does not talk about possession of anything, but rather the author of this sentence is asking where they are.