The roller assembly is ready to have the colored parts added, beginning with the cover. Slide it in, roll it up, then twist the RIGHT torque plate so that it tries to roll up MORE (CW). Put at least 6 full turns on it, then install the RIGHT end cap so the letter "R" shows, & then the left cap showing "L".
For the maximum tension on the cover (so it doesn't sag much, but may overstress the fabric & catch pins), leave it fully UNrolled. Wind up the R torque plate until the spring inside binds & stops. Then install the end caps and CAREFULLY allow the cover to roll up.
If you failed to mark the drum during disassembly, use this diagram to ID L & R ends: