As stated do NOT use silicone to seal your windshield or anything else as far as that goes. Somewhere along the seam, silicone will loose its adhesion and begin wicking water in like a pump. Silicone is good for appearances but never trust it to make a good water tight seal.
Take it to a glass shop and let them use their sealants and be done with it. And that's coming from a guy that never does all his own repairs - unless it's out of my league and take it from me, this is out of the league for almost all of us.