diff --git a/doc/using.md b/doc/using.md
index 0e365c96..6c3080c8 100644
--- a/doc/using.md
+++ b/doc/using.md
@@ -34,6 +34,21 @@ interchangeably: you can specify either at (very nearly) any time. A very
 common workflow is to read a disk to a flux file, and then reread from the flux
 file while changing the decoder options, to save disk wear. It's also much faster.
 
+### Connecting it up
+
+To use, simply plug your FluxEngine into your computer and run the client. If a
+single device is plugged in, it will be automatically detected and used.
+
+If _more_ than one device is plugged in, you need to specify which one to use
+with the `--device` parameter, which takes the device serial number as a
+parameter.  You can find out the serial numbers by running the command without
+the `--device` parameter, and if more than one device is attached they will be
+listed. The serial number is also shown whenever a connection is made.
+
+You _can_ work with more than one FluxEngine at the same time, using different
+invocations of the client; but be careful of USB bandwidth. If the devices are
+connected via the same hub, the bandwidth will be shared.
+
 ### Source and destination specifiers
 
 When reading from or writing _flux_ (either from or to a real disk, or a flux