Do you know what kind of heels are comfortable enough to wear while walking easily? And how can we purchase them?

I want to get some winter boots for myself. However, I'd want a set of boots that I could wear in both the winter and the summer. Do you know any reputable websites? Please let me know what you know if you do.

I want to buy sneakers, but I have no idea where or how to do it. Can you recommend any top applications to me?