If you are using Windows, press the green button, (Clone or Download) and then download zip.
Unzip the file to your computer as usual.
If you are using Linux, follow this link from GitHubHelp:
https://help.github.com/articles/cloning-a-repository/You will find many other helpful pieces of information if you read the Help page of MyEtherWallet.
Everything is explained there.
- go to offline and use that tx you created to sign using your private key using the repository clone you made in first step.
This might be a dumb question, but how do you "use" the repository clone exactly? I'd be interested in switching to an offline signing system like this, but I've only used the Myetherwallet browser GUI. Are you saying there's no GUI for doing this?