Go to the image that you want to use for this project. You can use any image, but keep in mind that a higher-resolution image will be easier to work with. Doing so prompts a drop-down menu. It's near the middle of the drop-down menu. A pop-out window will appear. This option is in the pop-out menu. Doing this will open your photo in Paint. Click the pencil-shaped icon in the "Tools" section of the Paint toolbar to do so. Click the Size drop-down box, then click the thickest line in the resulting drop-down menu. It's in the upper-right side of the Paint window. This will help create a boundary between the image for which you want to change the background and the section of the photo that you'll replace with a green screen. You can zoom in by clicking the + icon in the lower-right corner of the window. The best manner for doing this will vary depending on your image; for example, if the left side of your image is mostly background that you want to delete later, you can select the rectangle drawing icon, click Fill, click Solid color, and then click the Color 2 box and double-click the light-green option. You can then click and drag across the section you want to remove to block it out with a large green box. When you're done, you should have a green background surrounding your subject. Once you've added the green screen background to your image, save the image as a new file by doing the following:  Click File. Select Save as. Click JPEG picture. Enter a file name, then click a save location (e.g., Desktop). Click Save. Unfortunately, MS Paint can't replace your green screen with a different image; you'll have to use your preferred photo manipulation option (e.g., Photoshop) or video editor to do this. Since the whole background is the same color, any green screen editing should leave you with only your initial subject on whatever background you select.

TL;DR in Indonesian:
Carilah gambar yang ingin diganti latar belakangnya. Klik kanan gambarnya. Pilih Open with yang berada di bagian tengah menu buka-bawah. Klik Paint yang terdapat di dalam menu pop-out. Pilih alat menggambar. Ubah ketebalan alat menggambar. Klik ganda kotak berwarna hijau muda. Buatlah garis secara hati-hati di bagian gambar yang ingin disimpan. Isilah ruang di sekitarnya dengan warna hijau muda. Simpan gambarnya. Gantilah latar belakang hijau menggunakan aplikasi lain.