There are many different ways to put a foreshaft on cane. If you've got river cane, you might not even need a foreshaft.
If your arrow is made of a larger diameter cane, like phragmites, you can simply insert a wood shoot into the end (one that matches the hole) with a little glue, taper the phrag a little bit to smooth out the transition, wrap with thread or sinew, and you're done.
If the foreshaft fits loosely in the hole, you can cut slots in the end of the cane so that the cane will compress around the foreshaft when you wrap it.
Otherwise, you will need to make a "shouldered" foreshaft. This is where the inserted part matches the hole (or is a little loose) and the exposed part matches the outside diameter of the cane. One good thing about a shouldered foreshaft: you don't have to worry about using a node to butt up against the inserted part of the foreshaft.
Hope that helps.