You will find a ton of customized Emacs Elisp files on the Net.
Getting Emacs to recognise and load these files is simple. Create a directory in your home dir. Call it whatever you like, but something relevant such as "elisp" is good.
After creating the directory we need to let Emacs know where it is and what its called.
Open your .emacs config file. This is normally located in your home directory. It may be hidden.
You can open and edit it in Emacs:
Hit enter to get a list or type .emacs
Edit your .emacs file and add the path to your new directory:
; Tell Emacs where elisp .el files reside and load
(add-to-list 'load-path "~/elisp")
Add this near the start of your .emacs file before you start loading .el files.
Emacs now knows where the files reside. Start dumping your .el files in that directory.
When you want to use a new .el file, edit .emacs and add the name of the .el file. If I download "fancy.el", I tell Emacs to load it at startup:
Don't add the .el extension, just the name of the file.