The quote above pertains to Celia telling the Duke that she is in solidarity with her cousin Rosalind. If the Duke punishes Rosalind than he must punish her too. As for three important points:
-Orlando is upset that his brother Oliver is not educating him or spending any inheritance on him. The two brothers scuffle. Oliver gives Orlando part of the inheritance and tells him to take Adam, the trusted, servant and get lost.
-The second story revolves around the young Duke banishing his brother the old Duke.
-Rosalind the daughter of Duke senior falls in love with Orlando.
-Young Duke gets angry that Rosalind is in love with Orlando and banishes her to the forests. Celia joins her. They leave dressed as men to be safe.