ok, here's the function where I use all the stream stuff.
TMapTile is an object, only the picfilename property is important for here. picfilename is of course a string.

Code:
var
 GroundMap: array[0..31, 0..31] of TMapTile;

(...)

function LoadGroundMapFromFile(FileName: string): Boolean;
var
  FileStream: TFileStream;
  c: string;
  len: longint;
  x, y: Word;
 begin
   result := true;
   len := 5;
   x := 5;
   y := 0;
   setlength(c, len);
   FileStream := TFileStream.Create(FileName, fmOpenRead);
   try
     for y := 0 to 31 do
      begin
        for x := 0 to 31 do
        begin
          FileStream.ReadBuffer(c[1],  (len * SizeOf(Char)));
          GroundMap[x, y].Picfilename := c;
        end;
      end;
   except begin
    result := false;               
    FileStream.Free;
    exit;
   end;
  end;
  FileStream.Free;
 end;
sven