Instruction in 5 steps:

1. Prepare hardware, see schematic.jpg

2. Install the GUI-O from
https://www.gui-o.com]
https://play.google.com/store/apps/details?id=com.guio.guioapp]
on your smartphone

3. Open MS-Leonardof.ino
and program the Arduino Leonardo.

4. Open GUI-O on smartphone, connect with Bluetooth device (HC06)

5. Press the start button in the GUI-O application
(blue circle with the GUI-O symbol)

That's it.

Youtube video

//-----------------------------------------------------------------------
// Arduino Leonardo nano Joystic Bluetooth HC06
// GUI-O JOYSTIC 
// https://play.google.com/store/apps/details?id=com.guio.guioapp
// www.gui-o.com
//-----------------------------------------------------------------------
float xa = 0.095419;
float yb = 0.048638;

float x;
float y;

byte bt1;
byte cur;

//Setup-------------------------------------------------------------------
void setup()
{

 Serial1.begin(9600);
 while (!Serial1); //wait for connection to become live
  delay(1000);
//GUI-O Init
init_guio();

pinMode(21, INPUT_PULLUP);
}

//Main -------------------------------------------------------------------
void loop()
{
 joystick();
 
 while (Serial1.available() > 0 ) {

     String str = Serial1.readString();

     if (str.equals("@im1 1\r\n")) {

        init_guio();
     } 

     if (str.equals("@init\r\n")) {
        init_guio();
     } 
}
}

// Procedure Init GUI-O --------------------------------------------------------
void init_guio()
{
//GUI-O Init

Serial1.println("@sls 500");
Serial1.println("@cls");
Serial1.println("@clo");
Serial1.println("@gse COD:0 TSC:39");
Serial1.println("@guis BGC:#696969 ASR:0.449671");

Serial1. println("|BSR UID:bsr1 X:50 Y:25 W:99 H:50 VIS:1 ROT:0 RAD:1.5 BGC:#d3d3d3 SBGC:#d3d3d3 FGC:#d3d3d3 SHE:1 BTH:0.5");
Serial1.println("|LB UID:lb2 X:80 Y:48 ALP:0 SHE:1 ROT:0 URL:1 FGC:#FFFFFF FSZ:2 FFA:'font0' TXT:'www.gui-o.com'");
Serial1.println("|SI UID:six X:50 Y:25 W:5 VIS:1 ROT:0 BGC:#B0C4DE FGC:#FF0000 SHE:1 EN:0");
Serial1.println("|LB UID:lb0 X:50 Y:55 ALP:0 SHE:1 ROT:0 FGC:#FFFFFF FSZ:4 FFA:'font7' TXT:'GUI-O Joystick'");
Serial1.println("|LB UID:lb1 X:50 Y:63 ALP:0 SHE:1 ROT:0 FGC:#FFFFFF FSZ:3 FFA:'font7' TXT:'Arduino Leonardo'");

Serial1.println("|LB UID:lbcu X:50 Y:60 ALP:0 SHE:1 ROT:0 FGC:#000000 FSZ:1.8 FFA:'font0' TXT:'---'");

Serial1.println("|IM UID:im1 X:50 Y:80 W:60 H:60 ROT:0 SHVR:0.8 SHE:1 SHC:#404040 IP:'https://i.imgur.com/sG1LpQV.png'");

Serial1.println("|IM UID:imp X:50 Y:25 W:15 H:10 ROT:0 SHVR:0.8 SHE:0 SHC:#404040 IP:'https://i.imgur.com/tlDfn0k.png'");
Serial1.println("@hls 200");

}
// Joystick----------------------------------------------------------------------
// Porcedure Joystick
void joystick()
{
   x=analogRead(A1)*xa;
   y=analogRead(A0)*yb;
   cur=y+4;

  bt1=(!digitalRead(21));
  digitalWrite(5, bt1);

  delay(10);

  Serial1.print("@six X:");Serial1.print(x);Serial1.print(" Y:"); Serial1.print(y); Serial1.print(" EN:");Serial1.print(bt1);
  Serial1.println();

   Serial1.print("@imp X:");Serial1.print(x);Serial1.print(" Y:"); Serial1.print(y);
   Serial1.println();

  Serial1.print("@lbcu X:");Serial1.print(x);Serial1.print(" Y:"); Serial1.print(cur); Serial1.print(" TXT:'");
  Serial1.print("X:"); Serial1.print(x); Serial1.print("Y:"); Serial1.print(y);Serial1.print("'");

  Serial1.println();
}  

//---------------------------------------------------------------------------------