It's a white anvil on a dark-blue background. Doing so will open the Forge installer. If you receive a pop-up message telling you to install Java, go to https://www.java.com/en/download/ in your browser, click Free Java Download, click Agree and Start Free Download, and then install Java once it finishes downloading. If it isn't, click the box or circle next to "Install client" before proceeding. It's in the bottom-right corner of the page. Doing so will install the client files and folders for Minecraft Forge. You can change the destination folder by clicking ... and then selecting a new folder. This will complete the installation process.

TL;DR in Indonesian:
Klik dua kali ikon Forge. Pastikan kotak "Install client" sudah ditandai. Klik tombol OK. Klik tombol OK ketika diminta.