How to say who in german?

[Lauren Chu]

Like, "I was talking to my friend who works at Facebook."
This is the format we're using:
Ich habe Mein Freund ____________ gesprochen.
Thanks!

[Erik Van Thienen]

One possible construction is "... mein Freund, der für Facebook arbeitet, ..."

[David]

Erik's is fine and good. Don't forget to go back and get your own correct case for the action you want: "Ich habe MIT meinem Freund, der. ..." [Erik's]. The 'der' will stay the same because it's the 'subject' in that clause...

[Laura]

You could say "der..." or "welcher" .
In written language we use " welcher" more often but when we talk we almost exclusively use " der"

[Rain]

I was talking to my friend who works at Facebook : Ich habe mit meinem Freund, der für Facebook arbeitet, gesprochen.

[Rose]

Ich habe mit meinem Freund, der für Facebook arbeitet, gesprochen.

[zirp]

, der für Facebook arbeitet,

but that translates to "I have spoken with my friend who works for Facebook", while the original phrase indicates you were speaking to him at the time..