Steganography in Java. How can I hide data in only Red/Green/Blue bytes from image?

Question

I saw this example here where that program embeds a text message into the LSB of the Alpha byte of a pixel but I don't trully understand everything .How can I embed the information I want only in the LSB of the Red byte or the Blue byte or the Green one from a pixel ?

Here are the functions where I think I should work on(so you don't have to go to the site):

private void embedInteger(BufferedImage img,int n,int start,int storageBit){
    int maxX=img.getWidth(),maxY=img.getHeight(),startX=start/maxY,startY=start-startX*maxY,count=0;
    for(int i=startX;i<maxX && count<32;i++){
        for(int j=startY;j<maxY && count<32;j++){
            int rgb=img.getRGB(i, j),bit=getBitValue(n,count);
            rgb=setBitValue(rgb,storageBit,bit);
            img.setRGB(i,j,rgb);
            count++;
        }
    }
}


private void embedByte(BufferedImage img,byte b,int start,int storageBit){
    int maxX=img.getWidth(),maxY=img.getHeight(),startX=start/maxY,startY=start-startX*maxY,count=0;
    for(int i=startX;i<maxX && count<8;i++){
        for(int j=startY;j<maxY && count<8;j++){
            int rgb=img.getRGB(i,j),bit=getBitValue(b,count);
            rgb=setBitValue(rgb,storageBit,bit);
            img.setRGB(i,j,rgb);
            count++;
        }
    }
}

private int getBitValue(int n,int location){
    int v= n & (int) Math.round(Math.pow(2, location));
    return v==0?0:1;
}

private int setBitValue(int n,int location,int bit){
    int toggle = (int)Math.pow(2, location),bv=getBitValue(n,location);
    if(bv==bit)
        return n;
    if(bv==0&&bit==1)
        n |= toggle;
    else if(bv==1 && bit==0)
        n^=toggle;
    return n;
}