Arbitrum is a layer 2 scaling solution for Ethereum that aims to increase transaction speed and reduce gas fees. In order to use Arbitrum, you need to set up an Arbitrum RPC (Remote Procedure Call) endpoint. Here are the steps to set up an Arbitrum RPC:
Open your Ethereum wallet or DApp and go to the network settings.
Click on "Custom RPC" or "Add Network" to create a new network.
Click on "Save" or "Add Network" to save the Arbitrum RPC to your network settings.
You should now be able to select the Arbitrum network from the network settings and use it to send and receive transactions on Arbitrum.
Note that in order to use Arbitrum, you will need to have some ETH on the Ethereum mainnet to pay for gas fees. You will also need to have an Arbitrum wallet, which can be created using the Arbitrum One Wallet or other compatible wallets.