It is 21 GB. What difference does this make?
Well if you only have 777 items and that folder is 21 gigs that makes for 777 enormous items or something is wrong. That's why this might be important.
I need to understand how things work as far as this 'package' function goes. I understand you all need details to help me but it can also help if I could learn about how this programming functions. Is there a tutorial somewhere I should watch or something to this effect?
No there isn't. Simply, the Masters contain your photos as downloaed from your camera/device. The Previews contain versions for sharing via Media Browsers and the Data folder contains thumbnails. Thereafter you have a lot of database, metadata and versioning files and some caches.
"Make no changes to the library package." Why?
You'll trash your Library if you do. This is a rule that holds in about 99.95% of cases. This will result in dataloss for you.
I need to change something so that I have more memory space. Deleting didn't change anything, emptying the trash didn't change anything.
Yes, but as I said, in about 99.95% of cases you will not need to change anything within here, and doing so will cause you dataloss.
From my general understanding and experience with computers I would copy all the photos in all thes files and save them on my Airport Time Capsule.
And in doing so trash the Library resulting in dataloss as described.
The iPhoto library is not just a bunch of files and folders. It's a complex ecosystem of interlinked databases, folders and files. Breaking those links will cause dataloss. So you need to treat the Library as a unit, not a collection of its parts. One poster on here referred to it being like a car engine. You can just yank bits out and put them in the trunk of the car and expect it to work...
I don't feel like download what ever 'clean my mac' app or whatever cuz I don't feel I should have to make things more complicated.
That's the point. Don't ever donwload these apps. They're a waste of money and - not infrequently - they treat the iPhoto Library like a bundle of files and folders and thereby trash it.
Where next:
I'm guessing there are three possible reasons why 777 items weigh in at 21 gigs.
a: You've got some enormous videos in there.
b: You've had a lot more stuff in there in the past and when deleting it haasn't cleaned up properly
c: Something else is in there that shouldn't be there.
So, do you have very long videos?
Within the Masters package there are a bunch of folders. They're named for the date and time of import.
Sort these on size. Again, how large is the biggest? And what's inside it?