Replacing an outdoor junction box - need some help
Looks like you've got a 1 gang 5 hole outdoor electrical box, like this.

A couple weatherproof lampholders,

and a motion sensor.

You should be able to find each of these sold separately, at your local hardware or big box store. To replace them, you'll have to be comfortable doing electrical work, and working from a ladder. If you're not comfortable with either, contact a local Electrician to complete the repair.
Replace the broken bits
If you have no problems with this type of work, the repair is quite simple.  Start by turning off the power to this circuit at the breaker, and verifying the power is off using a non-contact voltage tester. Next remove the cover from the box, which is likely held on by two screws.  This will reveal the wiring inside. Take a moment to note (and jot down) how everything is connected. Taking pictures is often helpful.
Remove the lampholder
Locate the wires going to the broken lampholder, and follow them to where they connect to the other wires. Disconnect the wires from the broken lampholder from the other wiring (likely done by removing twist-on wire connectors), making sure to remember where they were connected.
There may be a locknut where the lampholder threads into the box.

Loosen the locknut with a pair of tongue and groove pliers (channellocks), then simply unscrew the lampholder from the box.
Finishing up
Installation is the opposite of removal.
Follow the same procedure to replace the motion sensor.
Before replacing the box cover, inspect the gasket and replace it if necessary.