Create campaign and resume later

Hope you'll pardon my questions but I'm new to MW by now :)

Using Interspire I was used to create a new campaign and work on it during several days adding content. When I've finished and the campaign is ready, I send it.

Now it seems to me that when I create a new campaign and I'm adding content, I cannot save the campaign and send it later but I've to finish and send it immediately.

How can I save my campaign in progress and send is as soon as it's ready?
Ok forget about it. My fault.

I've created a campaign and imported the template I want to use but how can I replace the images in the template? There's no way to upload a new image for example...