Please follow this guide for installing Geth with Windows, OSX, or Linux. To install Solidity, follow this guide for Windows, OSX, or Linux.
Assuming that you have Geth and Solidity installed, have an account and have some Ether's on you account.
An alternative to the Solidity Compiler is the online Remix - Solidity IDE.
To gain some Ether's use Ether faucet.
Open Terminal and start Geth :
geth --rinkeby --fast
In a new Terminal tab/window, attach to Geth and open the JavaScript Console
geth attach $HOME/.ethereum/rinkeby/geth.ipc
The HelloWorld contract has already been deployed. The contract address is 0xEC90Dc181274b3Aa38ec6d1f0d098aFE07D6a6f7. The transaction for the deployment is here.
To call the sayHello()-Method, open the JavaScript Console tab/window and execute:
var abi = [{"constant":true,"inputs":[],"name":"sayHello","outputs":[{"name":"","type":"string"}],"payable":false,"type":"function"},{"inputs":[],"payable":false,"type":"constructor"}];
var aimsHelloWorldContractInstance = eth.contract(abi).at("0xEC90Dc181274b3Aa38ec6d1f0d098aFE07D6a6f7");
aimsHelloWorldContractInstance.sayHello(); // OUTPUT: "Hello World"
If the output is "Hello World" then you have successfully installed geth and you are ready for the AIMS Smart Contract Lab.