You're barking up the wrong tree -- you don't need to create a new primary partition. What you need to do is to move the free space out of your extended partition in such a way that you can expand your primary partition into that space.
The details of how to do this vary greatly depending on your exact current partition layout. Such things are also often best described with diagrams. As one simple example, take the following part of the GParted documentation:
http://gparted.org/display-doc.php%3Fname%3Dmoving-space-between-partitions
This shows how to resize partitions to expand a primary partition that immediately precedes an extended partition with one logical partition, taking the space from the logical partition. If your layout differs from this, you may need to perform more partition moves or otherwise change the procedure. Some details will also differ depending on the tool you use (GParted vs. something else). If you need more advice, you should post details, perhaps including a screen shot of whatever GUI partitioning tool you're using (EaseUS, it seems).
One more comment: Moving and resizing partitions are inherently dangerous activities. Be sure you have adequate backups before you perform such tasks!
