There are a few different ways that you can transfer line from one reel to another. The most common way is to use a backing plate. This is a small plate that goes between the two reels and has a hole in the center for the line to pass through. You can also use a piece of string or fishing line to tie the two reels together. Another option is to use a special adapter that goes on the end of one reel and allows you to thread it onto the other reel. Whichever method you choose, make sure that the line is passing through smoothly before you start fishing.