If I remember well the limit of 4 primary partitions is for windows.
Anyway the way to do it, is to create an extended partition and then add logical partition.
So keep one or two primary partitions and make the others as logicals. Like this you can make almost as many partitions as you want...
AFAIK the 4 primary partition limit is an MBR limit (the partition table only has 'slots' for 4 partitions...so it's not a windows issue).
Anyway, as mentioned, you can work around this by creating extended partition(s) and creating logical partitions inside them.
Notes:
1. An extended partition counts as a primary partition (reserves one 'slot') so if you have one extended partition, you can only have 3 primary partitions etc.
2. Haven't run into the limit of logical partitions on one extended partition, but I recall reading it is 24 logical partitions on one extended partition (so in most cases a non-issue)
3. This information might be outdated, but I think windows needs to be installed on a primary partition (not on a logical partition)