In case you do not have Ethereum already you can either acquire some on an exchange in return for other crypto you might hold or in return for Fiat currency. In order to be more secure and to keep your privacy you might want to use a service such as Shapeshift for crypto or Changelly for Fiat.
Once you have acquired your Ethereum move it to your own personal wallet that you have full control over. In order to be more secure and keep your privacy you might want to make a fresh wallet that you did not use before. You could use a browser based wallet such as Metamask or a hardware wallet such as a Ledger.
Once you hold your Ethereum in your own wallet that you control you are ready to contribute to the project by send ETH to the following contract address: 0x7415c7bF3e2415Fa9A55f1Fd8B6FCcf2914C39a6
You need to make sure that both your Gas Price and Gas Limit are over the required values in order for your transaction to go through. For Gas Price the value is dependant on the Ethereum network load, so you should either use the recommended value of your wallet or look up that information on an online resource such as ETH Gas Station. For Gas Limit we recommend using a value of 120,000 or above.
In order to claim your tokens you need to wait for the plot that you contributed on to end. After that you can send any amount of Ethereum to the contribute address. Your ETH amount will be refunded and you will be credited the tokens based on your contribution in the plot. The claim address is: 0x61045DB805370df5255F95710B26Ddc578CE0B3A
After you claimed the tokens are already credited to your wallet. Depending on the wallet you are using you might need to run one extra step of adding the token information to your wallet so that they become viewable in the wallet interface.
Please check how to add an ERC20 token to your wallet and use the information available on the Tokens page.