Flare is different than Adobe FrameMaker, not just because it's a different product, but because Flare thinks about content differently than FrameMaker.
In FrameMaker, you use a book with files to define your content. The smallest chunk of information is typically the file, or chapter. You assemble a group of files into a book, which is your deliverable. You can use Flare the same way, in that you can open a topic and write a 50-page Chapter 4, but the real power of Flare will be missed.
In Flare, you don't work initially with chapters; rather, you work with topics. Similar to FrameMaker, you assemble the topics into the deliverable, but you will have many more topics than you had chapters in FrameMaker.
Topics are the unit of content that you should be working with in Flare. They are usually 2 to 4 pages of text, including any graphics. In most cases, topics will probably map to the headings (Heading 1, Heading 2, and so on) in your FrameMaker files.
Not all the information in every heading section should be a topic, though. For example, the information in your heading level 4s may not be able to stand on their own—this information may need the context of the information in the heading level 3 above it to make sense to the reader.
There are no hard and fast rules about the size of the chunks of information and how to break it up. In general, a topic should be able to stand on its own. This is where knowing the structure of your FrameMaker files is going to help you a lot.
