Love my Mac. No need to down play the fact that you have one.
Cant go wrong with Corsair RAM, just make sure its compatible with the laptop.
You would start by taking the back plate off of the laptop, unscrewing the CD reader and plugging in the 2.5in SSD.
Next, boot up your computer and open Disk Utility, select the drive (not the Macintosh HD volume), open the erase tab, set the format to Mac OS Extended (Journaled), and press the erase button.
After that, you can install OSX onto that drive via USB or right from your main boot drive (the HDD). To do so you'd need to partition the disk, which is also found in the Disk Utility app.
Take the time now to back up everything you want to save on your current drive, such as important documents and what not. You will not be able to keep them after the reformat. To back them up, simply use a USB drive/external drive, and you can drag everything over and save it there. Be advised, dragging applications will not work, so you'd need to reinstall/make sure that microsoft office is hooked up to an account you can log back into for word and what not.
After installing OSX on the new drive, you need to boot to that drive. Restart the computer when it is all finished and as soon as you see the screen light up press and hold the "alt/option" key on your keyboard. From there you should be able to select which drive to boot to via arrow keys.
Then, when you boot it might take you through set up and what not since its a new install. let it do its thing. This is when you say goodbye to everything on your old drive. Dont worry, you will still be able to use it, just not in its current state.
You're gonna have to erase your original HDD via disk utility, but make sure its still formatted under mac os extended journaled. After the reformat, then you will be able to use that drive in conjunction with your SSD that you have your OS installed on.
TL;DR there are several guides that take you through the process, or something along those lines. heres one from ifixit that somewhat deals with what you're getting into.
http://www.ifixit.com/Misc/HD_Software_install.pdf
Sorry for the LONG reply, but it had to be done. Hope I helped.