What documents do I need to file after started my business?

I am starting a eCommerce corporate soon and have been wondering what stuff do I need to file at the end of the year.

Files like:
- Employee Tax
- Hiring your first Employee
- Corporate incomes
Etc...

And what do I need to have such as:
- Employee Insurance
- EIN
Etc...
I know there are more and I did look it up on the IRS website, I just want to make sure I have all the important files and knowing what else I am missing. Can someone give me a full list for all the files that are require to file and needed?
I really apperciated for those of you taking your time to read this thread.:o:o