Your query makes absolutely no sense. It sounds like you just opened After Effects for the first time, and you expect that using it will be crystal-clear to a newcomer. Well, it won't. It never has. Perhaps it never will. So go here:
Start from Square One. Learn from the professionals. If there's anyone who needs to do that, it's you.
get started with AE:
If you are sure scripts are what you need and just want to find and use scripts, there are lots of them at http://aescripts.com/
Scripts are NOT safe in the sense that a script that you don't trust may, for example, delete any files on your hard-drive.
You can set an option in the AE preferences to disallow scripts to write files and access the network. This will makes scripts safer but also makes many scripts refuse to work.
I personally trust the scripts at aescripts.com, since they are peer reviewed by a great team. I also offer my own scripts there.