Transfer files through OpenFire clients

Hello. Tell me, please, where is written, how do OpenFire clients send files between them? Configured the OpenFire server on Windows. Messages are sent without problems. When transferring files between Pidgin clients, everything passes without problems. When using QIP and Pidgin, files are not send. Install Spark. With Spark on QIP are send, there is no back.
Perhaps someone already set up send files using the QIP client and there is a description? I did not find a detailed description of how to do this.

File transfer usually happens between clients without server participation (peer to peer). You should ask QIP developers about that.