WE DO NOT WANT TO STAIN THE NEW DOOR JUST PROTECT IT. SHOULD WE USE OIL BASE OR WATER BASE SEALANT ON THE EXTERIOR DOOR?

I have removed all the wallpaper and the border that was at eye level in the bedroom, I have repaired the walls, stained and washed the walls. Now after painting there is a shadow top and bottom of where the boarder was. Now what?? I have no idea how long