4 partitions on a 500gig drive is too many in my opinion these days when Windows can now handle partitions many tmes greater than that, and the latest apps are much more bloated than they use to be.
But if you must have 4, you can do it with the Disk Management console:
Control Panel > Admin Tools > Computer Management > Disk Management
In the bottom-right pane, find the ribbon which corresponds to your portable drive.
If you aren't bothered about losing any existing data on it, right-click that ribbon and choose "Delete Partition"
You will now see only "Unallocated" space on it.
1. Right-click & choose "Create Partition"
2. Select the size you want the partition to be, bearing in mind you need to make it small enough to leave room for three more.
3, When the partition has been created, right-click it and choose "Format".
When that's finished, repeat steps 1-3 until you have four formatted partitions.