- Go to https://optifine.net/downloads
- Click Download to the right of which Optifine you want depending on what version of Minecraft you want it for. E.g for 1.13.2 you want "OptiFine 1.13.2 HD U E5"
- Wait a few seconds, then click SKIP AD in the top-right corner of the screen
- Click the Download OptiFine link in the middle of the page.
- Click Keep or Allow if your browser warns you that OptiFine might be dangerous.
- Make sure you have already the version of Minecraft you wish to install Optifine with at least once.
- Select Open with Java if it asks you what software you want to open it with.
- Make sure the install path is C:\Users\owenb\AppData\Roaming\.minecraft
- Click Install
- A message should pop up saying it was successfully installed, click OK
- Load the Minecraft launcher
- The Optifine version of the game that you've just installed should be displayed under "play" in the green box at the bottom of the launcher.
- If not then click on the up arrow on the left hand side of the "play" box and select the correct version.
Congrats! you've successfully installed Optifine for Minecraft!