Access to Server and Real Data for Performance Tuning
Below is not complete (and longer than a comment)- since this is a very open ended question and will be closed (I am voting it to close as well).

I have laid below down to give you guidance and help you get started.


You have to install sql server. Go for a Developer edition.
download and restore Adventure Works 2014 Sample Databases
If you want to work with lots of data then - Enlarge the AdventureWorks Sample Databases
You can have open source data - e.g. stackexchange data and then import it into sql server.
Highly recommend to read this answer - performance tuning is an art not science .. and you will slowly and gradually master it.
Among many book that I have read, I would highly recommend T-SQL Querying by  Itzik Ben-Gan 



  Is there a company who provide education with server and real data?


Stackexchange does provide with data and an interface. Infact, Brent and his team utilizes this data to demonstrate query tuning.

Also, you can play with optimizer to lead it to believe you have a large data (this is very advance and would not recommend to any novice in SQL Server field)

UPDATE STATISTICS table_name WITH ROWCOUNT = 10000000000, pagecount = 100000000000