I think the answer to your questions requires a little closer look at what you're actually trying to accomplish. This hasn't become really clear yet. I think we're getting a few completely different things mixed up here.
Revolta is a software synthesizer. It can be sequenced via MIDI. You can't use it to replay audio files. It's not a software sampler.
The BeatBox is a little software drum computer that is based on samples. I guess, it does allow you to load your own samples and use them in the context of a drum set, but the options are limited. Also, it cannot be sequences via the MIDI Editor of Music Maker. It has got its own built-in step sequencer, and with this being a drum computer, it also wouldn't allow for melodic playback of the samples you bring in.
If you're really just looking for a very basic software sampler that will enable you to bring an audio sample into Music Maker and actually sequence it via the MIDI Editor, you can take advantage of Music Maker's VST support. Just download and install a plug-in like sfZed:
This is an extremely straightforward and easy-to-use software sampler that will enable you to load a simple audio sample in some standard formats and sequence it via MIDI.
Create a MIDI/VSTi object and input your little musical phrase via the mouse or your MIDI keyboard. Set the output instrument to sfzed via the "Instr." drop-down list. You might have to add the VST plug-in path with sfzed first, which you can also do in the drop-down menu from the "Instr." slot.