You want to create more partitions in your disks but your disk only allows up to 4 partitions only. Random google search tells you that your disk is in MBR format, and now you have to convert it to GPT. You have data on your disk so you want to convert to GPT without losing your data. So, the question is can you convert your MBR disk to GPT without losing data?
Short introduction about MBR & GPT
MBR only allows upto 4 Primary partitions, and windows allows to create some logical partitions. But the problem is, you can’t just dual boot from your MBR disk, and much upgraded and more secure UEFI bios won’t allow you to boot from MBR disks [Bootable USB images which are for installing OSes are another story].
On the other hand GPT allows unlimited number of partitions, however Windows will only allow you to create 128 [You don’t need that many partitions anyway]. In GPT you can dual or multiple boot OSes from any partition of the disk you have installed. And in this type of disks every partitions are primary.
If you wan’t to convert your disk to GPT without losing data, in short answer, you can’t do that.
In long answer, converting disks require you to format the disk because, when writing the partition table it will arrange as GPT requires. you can’t just overwrite partition table without losing data. It’s made that way. You have to do entire backup of the disk and then convert. Don’t just believe in random internet junk, you’ll lose your data.