First of all you will have to set up an account, and a dialogue box will appear where you will have to identify your Blog provider (in the case of this blog it is 'Blogger'). There is a pictures option but you need to be able to identify your own server to access the pictures, so it might be easier to leave the pictures alone and add them in the final stages. Once you have identified your provider, type in your User name and password that you usually use for editing your blog. Select your blog if you have more than one and then you can start typing in your new post. You can add more blogs by clicking on the Manage Accounts, going through the same procedure as before.
Now you can type your blog offline, save and return to it when you like.