Go to post office and tell them that you need to send fax. They will give you a paper to fill up and you have to put the number that you're going to send it to.

The post office doesn't receive fax, but you can tell them if it is possible for you because it's very important and that you need it urgently because you don't have fax at home.

If you want to express it in German which is better, let me know if I can help