The only way to non-destructively convert a Dynamic disk to Basic is using free Easeus Home Edition or free Partition Wizard version 4.2 which still offered this as a free feature: pw422.zip ISO - Windows Live.
Download and burn ISO to CD using ImgBurn, boot, click on HD # to Convert to Basic from Disk tab.
Here is a video tutorial: How to convert dynamic disk to basic disk with Partition Wizard?
If you created the fifth partition you may need to delete it first using PW CD to get it to convert.
I would save your backup image externally since it may need to be used to recover a failed HD.
To create new partitions, post back a screenshot of your maximized Disk mgmt drive map and listings so we can advise you which Primary partition to Convert to Logical which will allow you to add as many Logical sub-partitions as you want. In most cases this will be C if it is not marked System Active since the System boot files cannot reside on a Logical partition.