pre-compose with after effects

[taco salad]

After pre-composing all the layers in my timeline, how do I re-open the individual layers for editing? Also, the first layer, numbrer 1, the upper most layer, isn't included into the composition. I get an error message, saying it is missing. Does it matter that I shortened the work area to equal that of the composition? The project is complex, (lots of layers), so I thought pre-composing would be the best way to work. But after I pre-compose, I can still go back and edit, right? Thanks. The community is way more knowledgeable than the autobot.

[Rick Gerard]

When you pre-compose, there is an option to open the new composition. If you did not select that option, you can always double-click the nested. comp (your-pre-comp), it should open the composition and give you access to all of the layers in the timeline.