Brief description of the first two lines of if poem.

In the first two lines, we become aware that Kipling is speaking to someone..... telling them to keep their heads, in other words to keep calm. The words "when all about you, Are losing theirs" also alludes to a situation in which people are panicking, thus, keeping calm requires rising above the panick, not being drawn into actions of others, something that depending upon the situation is difficult to do.