If you leave your Staking wallet open, you will receive a reward because you help maintain a decentralized network. In order to start earning, your coins must meet the so-called mature time, which is 24 hours. The longer you have an open wallet, the more weight your coins carry. The maximum time is 1 week, then the weight no longer increases and remains constant. Resp. once you get a reward, the weight resets and slowly increases again. Staking does not burden your computer, because nothing counts. All you need is a normal internet connection.