Firstly, you'll need a pre-set up Apple Device, such as an IPad, an IPhone or an IPod 4th Generation or up.
Next, you'll need an email account, the same one that you used in your Apple ID.
Then, you click on the IMessage App icon.
It will ask you to sign in with your Apple ID.
Once you've signed in you'll come to a page that looks like this.
Click on the icon as circled above.
Now the keyboard should come up and you'll be able to pick a contact to send your message to.
Click on the plus button as circled above.
This page will come up. Swipe downwards on the contact names until you find the person you want to send your message to.
You can also click on the search bar and type in the name of the person you want to message to find them quicker.
Once you've chosen your contact you click on the type bar where you can type the message. Eg. 'Hi'.
Once they have read your message a speech bubble with 3 dots inside will appear. This means that they are writing a message back to you. You will also be able to see when they read your message.
Once your contact has replied, it might take a few seconds to come through. Once it's come through you'll be able to read it straight away. Now you can send messages to all your friends and family.
The creator of this guide has not included tools