Please tell me where my albums are located and how to access an album and it's pics from within other apps.
This is a common issue for people using Google Photos for the first time... Google Photos is not a local gallery application. It is a cloud-based photo and video management service. The things it creates exist in your Google account. So any album you create only exists up in Google Photos and there is no 'local' album that exists.
Everything about Photos is trying to encourage you to shift your thinking... Your pictures and videos are uploaded into Google Photos and it is that version that they want you to work with. If you want to share that photo or video outside of Photos, it will need a local copy to do so... and it will download the file if needed.
So, in a sense, they view the local, original copy as a locally cached version of the picture or video that is based in Google Photos.
Now, if you are someone who has spent years organizing things local on the phone, it might seem odd... But keep in mind that Photos has an extremely powerful and robust indexing engine. Depending on how your phone is configured (mostly if you have Google Location Services enabled), the need to organize your photos almost becomes moot. I can bring up every picture I took of my daughter at a recent trip to Disney.... my son playing baseball, etc. Every picture I've taken of clouds... you name it. It'll use facial recognition to automatically create albums, even my cat. A little while ago, my wife was pouring over thousands (and I do mean thousands) of pictures to find a shot of her brother wearing a hat. Took me a few seconds.
And if you load the Google Backup client on your computer, you can have every pic and video automatically sync'd to your computer... when the photo gets backed up to Photos, it will get pulled down to the computer. She makes handmade products and takes a ton of product pictures and they'll be sitting there on her computer by the time she walks over and opens the folder.
I finally got my wife to start sharing pictures, albums and videos through Photos... she won't admit it, but it's orders of magnitude easier than how she used to share them out.