First
You are going about this the wrong way, making it much riskier and just harder for yourself.
Before you touch the insides of your MBP you should have OS X, drivers and apps installed and working on the new drive with it installed in a USB (or Thunderbolt) external caddy or dock. Once everything is tested out and known to work then, and only then, do you swap the drives.
StarTech docks work great e.g.
https://www.amazon.com/StarTech-com-.../dp/B00KT3BEAS. You need to select the exact dock for the connections available on your Mac.. in your case with a mid 2009 13" MBP it only has USB 2, and will be slow, but that is still a better/safer way to first tackle an install of stuff before trying to swap drives. If you have already swapped drives then just leave it there and follow the instructions for making and using a bootable installer on a USB flash drive below.
Who knows what exactly you are doing wrong, you don't give us a clear description or link to what exact OS X install steps you are following.. the Western Digital instructions are about formatting a drive, that's a tiny step in what you need to do. If formatting a drive as HFS+ does not work then you system or the drive is seriously screwed. So what *exactly* did not work? What *exact* error messages did you get. Nobody can help you if you keep posting fuzzy nonsense. What actual OS X install instructions are you following? Common cause of confusion/probe,s is people running an OS X update when they need to be doing a full clean install of OS X on that disk partition (so you download an installer to the running system/boot disk, run that installer, point it at the installation target partition, not the current partition, and off it goes, or you make a bootable on say a USB Flash drive installer and boot that and point it at the new partition... which of those are you doing?). or trying to install OS X versions that are not supported on their hardware.
Worse case make a bootable installer on a USB Flash stick, boot to that on the Mac and then install that to the drive in the external dock (be careful not to install it to the existing drive). Start here
https://support.apple.com/en-us/HT201372