It is similar to an infinitive phrase. You separate the phrase with a comma and "um," with the infinitive of the verb after "zu" at the end.

I am calling in order to talk. Ich rufe an, um zu reden.

http://www.bbc.co.uk/schools/gcsebitesize/german/grammar/verbsinfinitivesrev1.shtml

this website explains it pretty well if I didn't fully answer your question