Hi Denise,
You can use align down the left hand side or you can use one move matter to the left mark making sure the vertical part is the same length as the paragraph and with the horizontal marks going from the left hand edge of the paragraph to where you want it aligned. In other words, you can use the move matter to the left mark for anything from a single line to a whole page.
Just one other point. Although it doesn’t make any difference to what you need to do, are you sure the paragraph in question is centred? i.e. both edges will be straight and the bottom line will be centred at the end of the paragraph, or is it just that the paragraph is further over to the right than it should be?