Some people consume the offerings themselves while others leave the offerings for the local fauna to consume (the spirits are said to consume through them).
Whatever you do, make sure the food can be consumed by you, local fauna, and/or decompose in a way that doesn't harm the environment (food typically doesn't, but I still would use more natural foods and less processed foods).
Libations are easy to dispose as all you have to do is poor them into the ground. Some people like to pour them into running water, like the sink or a river. It'd be pretty nifty if you left some fruits and veggies on a plate, pour your libations in a cirlce around them, and then came back for the plate once the food is gone. It can take a few days, and if it's not gone by then, just bury it in a shallow pile of dirt so it can be compost.