welcome to the forums!
there are different kind of "sound" or sample cd on the market - some of them just have a bunch of wave files on it that can be loaded easy if they are 16bit/44.1khz files.
some have the sample content in sampler specific formats that first need to be converted elsewhere on a computer.
also you have to check the file names, as they should not have long filenames and also not all start the same and only have different numbers at the end.
else it can happen that your samples named "fancy_drum_sound_1", "fancy_drum_sound_2", etc all just show up as "fancy_drum_" or refuse to load.
you also can burn your own sample cd just as a plain data cd, but be careful with nested folder structures that go too deep or with folders that have more than 256 samples in it, sometimes the mpc has trouble reading all the content.
from normal music cd you can sample like you would from a record - just go to the recording screen, change the input to cd and you can play, search and skip the tracks like on any other cd player. be aware that, like when resampling the main outputs, the recording meters will display no level, as the mpc then is automatically recording at the highest digital level.
have fun!
peace, jo
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