You can only create 4 Primary Partition. But you can as much as logical partitions.
So create a extended partition and under that create as much as logical partition you want.
*i.imgur.com/7OYIg.jpg
See, For Eg., I have created 4 Partition of which first 3 are Partition and last one Extended Partition as only 4 Partition can be created.
Now I have created 2 Logical Partition and some Free Space is there too under the Extended Partition. Here you can create any number of Logical Partition under Extended Partition.
So For Eg., If you have a 500 GB HDD. Assume First 3 Partitions to be Primary and of 60GB Each. Now create a Extended Partition of rest 320GB, as only 4 partitions can be created and this last one needs to extended in order to create more partition.
Now under this 320GB extended partition create as much as logical partition you want.