By uploading. With torrents, you download, and you upload what you download to others who download. You must upload ten forths of what you download on this site. Otherwise, you will not be able to download until you have a 0.4 ratio again.
Look for freeleech torrents as well, like the one I uploaded earlier today. Download doesn't count on those, only upload. Download those and seed the to get your ratio up
They upload while you download too. But normally download speed is much faster than upload speed, so it hurts your ratio. You could limit your download speed for a while, to let the upload do its job for your ratio.