When a teacher/professor asks you for a critical analysis of a text, he/she does not want you to actually criticize the play in terms of looking for errors or mistakes. What a critical analysis of a literary text involves is your opinion of the work and why you think the way you do. You can approach a critical analysis of As You Like It from several different perspectives; I (or any other person answering this question) cannot do this for you, as it involves YOUR response to the play, not mine. The best way to form an opinion about the play is to read it; watch a film version (or two) of it; and read some of the criticism that others have written. You can analyze any of its elements: plot, characters, setting, themes, symbols. There is no one correct way to do it. I suggest that you look at the summary and some of the criticism available on this site to help get you started.