Some ideas and perhaps (as a novice without previous DIY experience) methods
to study before you undertake this upgrade from original rotational HDD to an SSD
you need to really understand what is involved.
• Apple OS X and Time Machine Tips: (even w/o time machine, see tips)
http://www.pondini.org/OSX/Home.html
And there are hardware answers to this, which may help. If you format the new SSD
from the running OS X in the working system, on rotational HDD inside the MacBook
you can do that if you have purchased a 'universal USB wire kit' that has its own AC
power adapter and a means to run the 'bare drive' outside the computer first... Then
it can have the new correct 'Formatting & Installation' of the system (or: clone/copy)
before it is installed inside the computer. It can be tested & boot the computer from
the external wire adapter connection prior to removal of the original hard disk drive.
The software answer to making a Clone or copy of running system, to another drive
capable of booting or running the computer, can be had as demo-ware; one of the
favorites available is from ShirtPocket software, known as SuperDuper. It can also
be used to make backups that can be used to run the computer. Full clone backups.
http://www.shirt-pocket.com/SuperDuper/SuperDuperDescription.html
And the 'external bare drive adapter' to be able to prepare a replacement new drive...
This is a direction you should have been directed to attempt as a novice. The hardware
is under $30 (or plus shipping if nobody near your location has something to do this)
Here is an example of the device, from a reputable Mac-centric vendor of good standing:
an Adapter Kit w/Power. Fast, Simple, Plug & Play.
"The NewerTech USB Universal Drive Adapter is the perfect tool for accessing bare
drives without having to install them into a computer or drive enclosure..."
https://eshop.macsales.com/item/NewerTech/U3NVSPATA/
The macsales OWC company also has free instruction videos; these should be understood
before you have the computer apart unless you have a second working online computer...
You can find the one for how to replace a drive, by model build number; for each process:
• OWC Install Videos:
https://eshop.macsales.com/installvideos/
And there are those iFixit repair guides for Macs (among others) from their site:
• iFixit Repair Guides for MacBook/Pro (locate your model from three series shown)
https://www.ifixit.com/Device/MacBook_Pro
To prepare for some kind of event makes it a tiny bit easier; and if you also have
and use a Time Machine to backup to a Time Capsule or dedicated external drive
then you have minor safeguard to help recover from total loss. That's hardly enough.
Sorry to see your thread belatedly, or I've have add these ideas two days ago.
And in a week or so, you could have been set to do the swap of new drive with
the system cloned into it already; and tested. You can boot from an external drive
if it was formatted correctly and a system installed or cloned into it. That's a test.
{PS: if your Mac has a partition for BootCamp to run Windows or other OS, that is
another matter; as the partition for windows won't easily clone into a new drive.}
In any event...
Good luck & happy trails! 🙂