First of all, ask yourself, what kind of map do you want to upload - a shape for a raster file?
For raster maps it is easy. Create a sub model, open up the sub model, and type the specified dimensions of the number of rows and the number of columns as in: 23,40
Within the sub model create a variable with a fixed parameter.
If you run this model, you will be asked for a 23x40 matrix. Browse to a "*.csv file" with 23 rows and 40 columns and load it up.
The shape (i.e. polygon) maps are a little more complex. Each of the polygons must have an id number. Each of the polygon ID's are then assigned a number of x and y variables that you need to substract from a shape file.