To get to Disk Manager, start at the Start button. From its menu, RIGHT-click on "My Computer" and choose "Manage" from the options. In the resulting window expand "Storage" if necessary and click on "Disk Management".
On the right in the upper pane there is a list of all the devices Windows knows how to use right now. In the lower right pane (scrollable so you can see them all) are blocks representing all the hardware devices in the machine, including ones Windows can't use yet like a new empty drive. For each block there will be a small box at the left showing something like "Disk 0" and a size and status. To the right of that there will be other blocks. For a new unit it likely will just have one large block called "Unallocated Space". If you RIGHT-click on this you'll have a small menu of choices and you can Create a Partition. Choosing that probably will get you a Wizard to help. You can choose the size of the Partition, its type, whether or not it is bootable. When you get to Formatting it (may be included in the Wizard, or you may have to do manually AFTER the Partition is created) you specify the file system (use NTFS unless you know you need FAT32) and a Quick Format unless you want to spend time on disk testing. When it's done it should have a letter name assigned to it.
The Partition, once created and formatted, will show up now as a new block in this device. If you RIGHT-click on the Partition's block you have some options including Change its Name - you can change to any letter not in use now. A drive Partition must have a letter name for Windows to use it. When you have done all you want in here, exit out of disk Manager and reboot to let Windows set all these thing up in the Registry. My Computer will show you your new drive ready to use.