There is a start.bat file in the Claymore directory. This is called a batch file. It can be setup to run when your computer turns on. You need to do a couple things first.

1. Set your computer to automatically login to windows on reboot and not require username/password.
http://www.howtogeek.com/112919/how-to-make-your-windows-8-computer-logon-automatically/


2. Make a shortcut to the claymore start.bat file and put it into the windows startup folder
http://www.howtogeek.com/228467/how-to-make-a-program-run-at-startup-on-any-computer/


You don't want to mine at ethpool. You won't get paid for weeks at a time because of the way they divide work.

At ethermine (run by the same people as ethpool), nanopool, or dwarfpool  you just need an ethereum wallet address. You don't have to signup to mine on those pools. You just need to specify your ethereum wallet address.  Follow the instructions in Claymore's readme.txt and replace his wallet address with your own.  You can use worker names like "worker1" "worker2" and "worker3" to identify your 3 different rigs so when you look at your stats on the pool you'll know which rig is which.

Hope this helps.
 

Start with BIOS settings on motherboard.  You usually have three options after a power loss event:  Shut Off, Turn On, Return to Previous State

Next would depend on your operating system.  For Windows, add program to startup folder.  For Linux, add program to Startup Applications.

Follow the directions provided on the pool website.  If you are just starting, I would get some equipment (maybe just one video card) and get that up and running.