This is assuming you want to use OpenCore Legacy Patcher, which allows for macOS Big Sur-Ventura.
Step 1 - Download OCLP
Go to
this link, scroll down to assets and download "OpenCore-Patcher-GUI.app.zip". You will want the latest release, 0.6.7.
Step 2 - Create a bootable macOS installer using OCLP
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Note that I'm running a newer "nightly" release of OCLP, however it will look the same for you.
1. Click on "Create macOS Installer".
2. Click on "Download macOS Installer".
3. Choose the release that you want to install. 11 is Big Sur, 12 is Monterey and 13 is Ventura. I would choose Monterey, as that is still updated and is faster than Ventura on machines that don't support Metal.
4. Wait for the download to finish. While waiting, insert the USB drive that you want to use. If possible, use a USB 3 drive as a USB 2 drive will be painfully slow to flash and install from.
5. Once the download has finished, a prompt will come up asking you to select a drive. Make sure to click the correct option as it lists all drives, including the OS drive you are booted of. It will be the option which is the same capacity as your flash drive, eg: 16GB, 32GB...
6. Once it has flashed the installer to the flash drive, it will ask if you want to build OpenCore to your newly flashed USB installer. Select "Yes", and wait for that to complete.
7. Once that is done, it is time to install macOS!
Step 3 - Installing macOS
1. Shut down your computer. Make sure that you have a Time Machine backup of your system in case something goes wrong. It's highly improbable that anything will fail, but you don't want to be stuck with a broken Mac.
2. Hold "Option" as soon as you press the power button. Select the option with the OpenCore logo (a blue square). It should also say something along the lines of "EFI Boot".
3. Once the installer has loaded, go into the Utilites menu at the top of the screen and click on Disk Utility.
4. Go into the View menu at the top and click on "Show All Devices".
5. Click on your SSD in the sidebar. It should look something like this, but with a different drive name:
View attachment 2230113
6. Click on the "Erase" button on the top right. This will erase your drive, giving you a clean slate to install macOS on. Make sure that the drive settings are "APFS" and "GUID Partition Map". They should be the default choices.
7. Exit Disk Utility.
8. Follow along with the prompts to Install macOS. From this point on, everything is simple.
Step 4 - Post-Installation
1. Once macOS has been installed, you may feel that things are a tad slow. Don't worry, that is normal. Hop into Safari and download OpenCore Legacy Patcher (the same link as in Step 1).
2. This time, once opened, you are going to select "Build and Install OpenCore". This will make it so you don't have plug in your USB stick every single time you boot your Mac up. Without OpenCore, macOS will simply not boot.
3. Once the build has finished (should only take a few seconds), select "Install to disk" and click on the SSD that you've just installed macOS on. This typically is highlighted.
4. Typically on first install, "post-install patches" should be installed by default. Among many things, this is what gives you graphics acceleration. However, after each macOS update, it will prompt you automatically to reinstall the root patches. Make sure to click OK.
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This is what the prompt looks like. Your patches may be different.
That's it. macOS is now installed with OpenCore.
I highly suggest also reading
the official OCLP guide, it is layed out really well and has lots of helpful info for troubleshooting.