Custom products in magento 2

Could somebody exert in Magento please tell me in a simple manner how I do this: I have a lot of rings to sell with different sizes, I need each product to have selectable size menu and each size has different price, so when you change the size the price also changes. I want to do exactly like this: [login to view URL] change size of shoe and the price changes. I couldn't figure it out using different tutorials, because I am new in magento and it is pretty complex! I will pay you to teach guide me create products with changeable size, color etc and dependent price.