'It is the first door on the right.'
'The first number is 3.'[Note: bangou most commonly means phone number, but here it wouldn't make sense]
"Migi" is a Japanese word and in English it means "Right"
'(These/Those/They) are our parents.'
'(This/That/She) is my younger sister.'
'It is the second door on the left.'
"Shita" is a Japanese word and in English it means "Down"
Where's the bathroom.
I think you mean "genki desu ka". The correct way of spelling it in English would be "ogenki desu ka". It is Japanese for "How are you?" One would usually answer by saying "Genki desu. Anata wa?' which means "I'm fine, and you?"
"O-ai dekite ureshii desu" is a Japanese phrase and in English it means "Nice to meet you"
'The third number is 7.'
'The second number is 9.'
If you mean the direction 'right', we call it migi in karate.