Oasis Network's Consensus Layer is a decentralised set of validator nodes that maintain a proof-of-stake blockchain.
Hence, it needs a set of distributed node operators that run different nodes (including validator nodes).
Then proceed by following the Run a Validator Node guide to:
Create your entity.
Initialize and configure your node.
Put enough stake in your escrow account.
Register your entity on the network.
To become a validator on the Oasis Network, you need to have enough tokens staked in your escrow account.
Currently, you should have:
100 ROSE staked for your entity's registration since that is the current entity's staking threshold.
100 ROSE staked for your validator node's registration since that is the current validator node's staking threshold.
Enough ROSE staked to be in the top 80 entities (by stake) so your validator will be elected into the consensus committee.