is it just like that I just contributing to the Bitcoin Network?, if it's true, then I won't do anything more.
Running a Bitcoin full node is your contribution to the network, the more time you run your node, the more contribution you do.
Bitcoin nodesYour Bitcoin full node will connect with other nodes, store Bitcoin blockchain data on your device as a copy, share it to other nodes and validate as well as relay new blocks and transactions.
Nodes don't confirm transactions, miners do it, nodes relay these transaction information to other nodes.