Windshield leak..

[Homieazteca]

I have read a couple of threads on this subject but not with this particular case.

I noticed a bit of moist under the carpets on the passenger side, but I just discarded as that, moist.
Never the less, it stuck to mind (also I heard few stories that started similarly)

Now it has been pouring rain for a week and now I think I can see where the leak is coming from, if I look from the inside seems to be where the two sheets of metal (roof and pillar(?)) and the windshield meet. the roof lining behind the plastic pillar cover is damped (only a small section) and I could see that it would run down with the door seals (in the inside) down to the footwell. I don´t think is a big leak cause it not that much but still I´d like to fix it.
Question is; can i diy it or need pro?
what kind of glue, cement, liquid, pad, do I use, and if somebody can gimme tips, greatly appreciate it.
thanks