To assign an audio file/sample from your USB Stick or SD card to a pad on your MPC standalone console, please check through the following steps:
1. Open the Browse menu
2. Select your USB Stick or SD Card
3. Select the audio file you want to use as a sample, then click Load
4. Click Sample Assign in the bottom-left corner of your display
5. Drag and drop the sample that you loaded from the Sample Panel on the left to your chosen pad on the right
6. Go to the grid of your track, start recording, then strike the pad you chose, which will in turn trigger the sample in the recording of your track