如果你看到这条信息了，就给我回信。翻译成英文

If you see this message, just give me reply

Please answer me the moment you recieved this

message !

the moment 一..就

(Please) Reply as soon as possible.

完全的意译.
像那种"如果你看见了就..."其实完全在表达多余的意思...
因为他肯定看见了..

please write back as soon as you 've read this message(note)

If you can get this message, please reply to me.

If you see the message ,please write it back to me