The file format should be the following:

x;x;...;x
x;x;...;x
...
x;x;...;x

The value for x must be either 0 or 1. Rows must have equal length, and the number of items per row must not exceed 20. The number of rows must not exceed 10 000. A typical way to create such a file is using Excel. Once your sheet is filled with your data, choose Save As, Other Formats, and CSV (Comma delimited) (*.csv).