Front / read windshiled gasket replacemnt

I noticed a few spots on my windshield gaskets (front and rear) that don't look so good. I have had the car out in the rain yet but with all of the work I have been doing I don't want it raining inside of my car! Plus I would like to make sure there is no rust in the channels.

How hard is it to do? I have never done a windshield gasket before, is it something you can learn fairly quickly? Does anyone know of a good toturial or video I could use as a reference for a step by step? Thanks in advance.