You can say : 잘 오셨어요 (honorific) 잘 왔어요 (polite, but not honoific) 잘 왔어 (casual, friendly) Normally, we don't use this verb, "환영하다" because it's quite formal to say.

hapmida is correct Wecome (오신 것을)환영합니다. to Korea 한국에 welcome to korea 한국에

한국에 오신 것을 환영 합니다 = hanguke osin gutsul hwanyoung hapmida

당신의 환영 cowboy...