By default the DualShock3 doesn't work on a PC without installing Motioninjoy or
SCP DS3. It gets detected as a USB-device but not as a controller, so Xpadder isn't detecting it. If Xpadder does detect it, a driver of a third-party PS3 controller is interfering, but still there will be be input.
After installing Motioninjoy you need to start it's DS3 Tool, select the section "Driver Manager", tick your controller in this chart and click on Load driver. If that is done, it should state in the column MotioninJoy "loaded".
Then you select the section Profiles, select either DX-Default or Xinput-Default and click on
Enable. You need to do this step every time you connect the controller/restarted your PC to make the analog sticks working and to have a look at the ads (this is why I prefer SCP DS3).
In the end the the controller should be called "MotioninJoy Virtual Controller" (in Xpadder as well as in the Game Controller Control Panel) and LED 1 should be lit up and not all of them blinking.