You can't test caps in circuit unless you use something like an ESR meter. Diodes are easy to test for; the first thing you do is set your multimeter to diode mode, place the red probe to the anode end and the black probe on the cathode (the end marked with a stripe). You should be getting some kind of voltage value when you do this. Then, flip the probes around and if the diode is good, you should not be getting any reading. Diodes are supposed to allow current to only flow in one way, so if there's a busted one then you have a problem.