As per the requirement I need to know is there any design tool available for SQL Server 2014 . Also I want to more Explore the performance Tuning and optimization for written code.
If you're looking for free tools then Windows 'Performance Monitor' is pretty helpful. You can add the specific counters that you want to monitor and keep track of them. There is a simple 'how to' guide here that will show you how you can store them a SQL Server instance then you can manipulate it how you want.
For performance tuning queries, it comes with practice. Find some poor queries and then look at the execution plan and see what its doing. There are many free videos that you can watch that will help you understand what it shows.