First things first - please download, read, sign and return the license agreement
Then, if you have not already, please join the DiFX-Users group hosted at Google Groups - to do this, go to http://groups.google.com/group/difx-users/ and request to join. Please make use of the field which lets you describe yourself, and include information on your affiliation if any and your interest in DiFX (the list does get some spam applications, and this makes it easier and quicker to approve real applications).
You might find it enlightening to browse the SVN source tree on Trac (but you will need to get an account on the SVN server; see the installation instructions for this. But you must join the difx-users group first!)
Read the Reference Manual which has a lot of detail about the NRAO installation of DiFX and a lot of information about the helper programs for configuring the correlator and managing the output.
How to correlate using different binaries on different cluster members
How to correlate directly off a Mark5 unit
How to correlate targets which are near-field objects such as spacecraft
Description of how to run benchmarking of DiFX
See VLBA sensitivity upgrade memo 32 for a description of how to set up pulsar observations
mpifxcorr documentation
vex2difx documentation
difx2fits documentation
difx2mark4 and hops documentation
difxfilterbank documentation
difx_monitor documentation
Utilities documentation
difxmessage logging information
vdifio vdif access libraries
espresso (scripts for managing file based correlation) documentation
Subversion tips and tricks
Description of correlator amplitude scaling
DiFX2.0 explained - the differences between DiFX1.5 and DiFX2.0
A description of the way channelisation works for upper and lower sideband data
Notes on optimizing the machine file
Using DiFX with non-power of two FFTs (beta!)
The DiFX memory size/datarate calculator (now available as a C program in the difxio library)