If you send a transaction to the network, then one miner-node will at some point pick it up. The Miner will run the transaction and add the result to the next block. Now, this doesn’t imply consensus yet. By design all nodes don’t trust each other. Each node must verify that the transaction the miner added to the block is really valid. This means, consensus is reached by having every node running the same transactions again and verifying that the result is correct. Plus, the results are verified in a cryptographic manner.