I would install a Samsung 830 as a first choice at least 128GB in size, or more. Other SSDs depending on price.
It is very easy. All you need to be able to is loose some screws, plug it in, fix everything back in place. Run Carbon Copy Cloner and copy the system drive.
Depending on how much data you have and how you want to have it setup there may be some stuff a little bit more complicated but there are like a thousand threads in this forum already that cover every aspect.
Just search. Some explain very detailed what should do.
I got a Sata 2 SSD in the optibay of a 2010 MBP with a 1 TB HDD in the main bay.
Just don't pay for those obscenely expensive MCE optibays. The ones on ebay cost a fraction and are just as good. There is no special magic to those things.