There is no simple way to do this. Nothing is built into Word.

Workaround:

1. Center your first line.
2. Type your second line left-justified.
3. Set a tab setting at the start of the first line. (or) set a Left Indent for that line at that point.
4. Press the tab key at the beginning of the line. (not needed with the Indent)
5. Pressing Enter at the end of your line will give you the same formatting for the next line.

Easier workaround but not as precise:

• Set a left indent that approximates what you want for all poems and use a style formatted with that indent for all lines.
• The first line will not be exactly centered many times, but should still be close enough. If it is not, move the indent for the poem to the point where the first line is centered.