In my own experience with Ojibway and other Native people, a "feast", even on an occasion with spiritual overtones, can be simply a big dinner or banquet, without any ceremony or ritual unfamiliar to the rest of us. You should, of course, be ready to make a little speech thanking everyone for coming, cooking, putting on the event, lending the chairs, etc. It would also be appropriate to say some words about your late wife. Native people, generally speaking, are quite familiar with loss and pain, and (contrary to the stereotype) emotional expression. If you weep, no one will think less of you. On the other hand, if you simply make a few stock, gracious remarks, that will be perfectly acceptable as well.

I don't think there will be much more to it than that - just a little friendly dinner to mark the occasion. Maybe someone will make a prayer. If there is a ceremony, it will commence with the burning of sweetgrass (in a clam shell, or some manner of ashtray), and you will be invited to go through the purification ritual of bending over the sweetgrass and scooping the smoke over your head. Nothing tricky to that, just do it as you see the others do - but if you choose not to do it at all, no one will be offended.

I once participated in a ceremony in which an Ojibway friend honoured and spoke to her ancestors - an integral part of this was giving a portion of the feast to the ancestors; this was done by filling a plate as you would for any guest, and then putting it into the fire. If you have a fire, by the way, bear in mind that in this context it is a spiritual entity, and is to be treated with appropriate respect. Don't be the first one to start throwing garbage into it .... !

If your friends bring an elder or elders - such as their parents - make a point of welcoming them to your home, and honouring them generally.

Listen to what your friends say to you - they are unlikely to tell you what to do, but they will give you hints if there is something that they would like you to do.

Finally, if you do feel that you have somehow offended someone, find some way to give them a gift or do something (in an obvious way) for them later on - they will understand it as an apology, and all will be forgiven.