In order to guide you on this, it is important that you understand the emphatic structure. First: Emphatic refers to emphasis. A simple emphatic sentence is one that makes a definite statement. Examples of simple emphatic sentences are: "I did wish it!" "You did not say that!" "I will go there!" It was her!" "Put that down!" and such as this. But this is not the end of the usage of emphatics.
Second: There may be emphatic questions and emphatic responses. These kinds of emphatics use the auxiliary verb do in the capacity of an operator do, also called a dummy do. Third: Let's explain what this concept means.
Auxiliary verb do is used in the construction of questions in past or present tense or future construction. Take a declarative statement, "I like figs," and turn it into a question by inverting word order and inserting auxiliary operator do: "Do you like figs?" Now, create an emphatic sentence with operator do: "I do like figs." "You do like figs." You may even negate the emphatic: "I do not like figs." "You do not like figs ... you are allergic." You can even be emphatic in the past tense or in a future construction: "I did like figs, but not anymore." "He does want to attend the fig fest."
In context of your question, you are asked to pretend to be Rosalind. Rosalind was without doubt very surprised to see Orlando in the Forest of Arden. The last she saw or heard of Orlando before running away from Duke Frederick's court was that he was the new wrestling champion and worthy, as such, of new honors and opportunity. Yet, here he is, hiding now in Arden Forest writing very poor poetry on trees! If Rosalind had been more direct in her response to this sudden new turn of events, she may have been very emphatic indeed.
Bear in mind that when Rosalind learns in III.ii that the tree poet is Orlando, Celia has already diffused some of Rosalind's reaction by teasing her with playful word games and remonstrances (i.e., scoldings) for not knowing instantly the poet was her own Orlando:
Is it possible?
O wonderful, wonderful, and most wonderful
wonderful! and yet again wonderful, and after that,
out of all hooping!
What Rosalind says in III.ii does not state her emphatic reaction, aside from "Alas the day!" but emphatics may be constructed from the string of questions she asks. For instance, we might construct one emphatic declaration as, "Oh! But I do look like a youth. I do want to look like a fair maiden before Orlando's eyes." Another might be, "I do not know how to meet him as myself yet be my other self in doublet and hose. I do want to know where he is at the moment."
You can now go on to construct further emphatic sentences from her other questions, such as: "What did he when thou sawest him? ... How looked he? Wherein went went he? ... Did he ask for me? Where remains he?"
Alas the day! what shall I do with my doublet and hose? What did he when thou sawest him? What said
he? How looked he? Wherein went he? What makes him here? Did he ask for me? Where remains he? How parted he with thee? and when shalt thou see him again? Answer me in one word.
But doth he know that I am in this forest and in
man's apparel? Looks he as freshly as he did the
day he wrestled?
One must remeber that Rosalind is in disguise. Seeing the man that she loves and not being able to express it would be difficult and at times exasperating. Although it seems as if the perfect way to find out his true feelings, Rosalind has to put on an act and not seem too suspicious. If he finds out that truth, that Galymeade is actually Rosalind, he could lose all his trust for her. Rosalind would of course be very happy to see Orlando, and this happiness would burst out of her at inappropriate moments, especially since she must act as if she does not know him. Rosalind's thought would run from love-stuck to frustrated as her true feelings are kept hidden.