Where do I find the migration docs?

I very recently installed 6.x and it works fine but my users want to be able to upload pictures in their posts so I want to go to 7.0.  I have downloaded it to my PC and I'm testing it in IIS before uploading to the server.  But I can't seem to find any documentation about upgrading from one version to the next.  I know from this forum that the database needs to be changed. Can you please point me to the filename or product I should be using?

Thanks!