How do I use Uniswap exchange?

I'm curious to know, how exactly do I go about using the Uniswap exchange? I've heard it's a decentralized platform for swapping tokens, but I'm not sure where to start. Can you walk me through the process, step by step? Are there any prerequisites I need to have in place, like a specific wallet or a certain amount of cryptocurrency? And what kind of fees should I expect to pay for using Uniswap? Any advice or tips you can offer would be greatly appreciated.