mirror modifier problem

so i’m quite a beginner, and i’m modelling this very simple character, i used the mirror modifier, then when i applied it, the middle edge, the one that was seperating the real half from the mirrored one, is sharp, and i cant smoothen it, so how do i do it? i know its a stupid question but its really annoying and i cant solve it

Ensure there is no internal face in the mesh along the mirrored plane. Ensure the centre vertices are actually merged (options in the mirror modifier).

Post a link to your blend file

animation project3.blend (686 KB)

that’s the character

You have edges close together along the centre of your object. These with the subsurf modifier will cause pinching. Spread the vertices remove the extra edges or spread them more evenly

thanx a lot