Hi Skoller,
I'll try to explain, but as I'm not a native English speaker, I'm not sure whether I make myself understood.
Under each door frame, there's a piece of panel attached to the body of the car by bolts and nuts.
Loose them and insert a P shape bulb seal, which can be found here Rubber Seals, Bulb Seals, Sponge Seals, U Section Rubber | Clark Rubber.
Tighten the bolts and nuts.
Done.:D

