Where are you from?

Dochira kara desuka . : Where are you from?
dochira : where
kara : from
desuka : is?
Dochira kara desuka : where,from,is? : Where are you from?

Dochira kara kimashitaka: Where did you come from?
kuru : come
(ko-nai,ki-masu,kuru,kuru-toki,kure-ba,koi,koyou,kita)
kimashita : came (past pattern of "ki-masu")
kimashita+ka : "ka" makes the word interrogative.
Dochira kara kimashitaka.: where, from, came? : Where did you come from?