Click on Options and select GUID Partition Table. Hit OK. Then click Apply.
When the system asks you if you're sure you want to partition the disk, click Partition.
Now wait while the disk is formatted as HSF+ so it can be used with CCC. This could take 10 to 20 minutes depending on the size of the disk. Your mileage will vary.
Now that you've formatted the external drive, it's ready to accept a clone of your local Mac hard drive.
There are many methods to use, but here's the easiest way to use CCC to clone your local hard drive onto the new one. Under Source Disk, select your Mac's local hard drive. That's Macintosh HD.
Next, select Target Disk. In this case, it's the external drive you just formatted. Notice I named mine CCC. After that, select New Disk Image.
In New Disk Image, you'll be able to choose additional settings like encrypting the disk image with a password and compressing the image to save space. Make your choices depending on what you need. When you're done, click OK.
You should now have your local drive set up as the Source Disk and your new drive as the Target Disk. Remember, I called mine CCC. Under Cloning Options, select Backup Everything.
Click Clone. Enter your user password if you have one. Click OK.
Now the cloning process will start. It will take at least an hour to complete.
Creating a clone of my hard disk with 34 GB of data took just over an hour.
When it's finished, you'll get a message notifying you that CCC is finished. Click OK to close CCC.
Now keep the external drive in a safe offsite location. That's a best practice, of course, unless you intend to install the newly cloned drive immediately or have another urgent need for it. Just don't forget where you put it!