First analyze the file with some notepad, is it text or binary data?
You don't rally need a sample, also without access to the actual file this demand seems irrelebvant, in a first step replace the definition of field of your internal table with character type with enough length. set a break-point after the GUI_UPLOAD so analyze what kind of data you actually get.
Then loop and try to map data field by field. As I already wrote, from simple MOVE statements to call of conversion-exit FM or even some ASSIGN CASTING.
Regards,
Raymond