Start WinDbg
Open the dump file. (Ctrl + D by default)
Tell WinDbg to go get the correct MicroSoft symbol files. Type .symfix. This may take a few moments as it will pull a ton of stuff down from the Internet.
Tell WinDbg where the symbols (PDB files) are. Type .sympath+ c:\pdblocation, substituting wherever you put the PDB files for the pathname. Make sure you get the plus sign in there with no whitespace between .sympath and the + sign or else you'll screw up step 3.
Tell WinDbg where the source code is. Type .srcpath c:\app_build_1.0.100 substituting the path where you got code from source control for this version of the software.
Tell WinDbg to analyze the dump file. Type !analyze -v