In Arms and the Man, what advice does Catherine give to Raina at the beginning of the first act and why?

In the first act, Catherine advises Raina in two areas.

The play actually begins with Catherine imploring Raina to go back to bed before she catches her cold. Later, Catherine advises Raina to stay in bed after the maid, Louka, announces that Serbian fugitives are on the loose. To make sure that Raina is safe, Catherine orders Louka to close the shutters in Raina's bedroom.

Catherine also advises Raina to treat her fiance, Sergius, with a greater measure of respect when she sees him. She scolds Raina for making Sergius wait a year before she would consent to be betrothed to him. In Catherine's mind, Sergius deserves better from Raina because he has just proven himself in battle. Apparently, Sergius is 'the hero of the hour.'

In supposed defiance of his Russian commanders, Sergius has led a charge against the Serbians and scattered the enemy. When Raina hears of Sergius' exploits, she becomes starry-eyed and implores her mother not to tell Sergius about her previous doubts of his military prowess. Catherine, for her part, advises Raina to never doubt the courage or the fortitude of their Bulgarian forces. She tells them that, although the Serbians have Austrian officers, the Bulgarians have managed to defeat them in every battle.