You can import audio files over iTunes or iCloud. You can also import from your pc or mac over the iTunes or iCloud clients.
All effects are in the free version available. Please define a selection for this. (Round buttons) In the free version you can save in the flac, wav, m4a, aac and wma format. Choose one of this formats in the filepicker.
Please define a selection to apply the functions. (Round buttons upstairs of the curve) See the tutorial at Define a selection