Hi guys, I’m new to both blender and the forum so be kind 
I have a cylinder in my project, and I want to subdivide the top face so it has a couple of extra verticies. I have followed the “w key, subdivide option” and selected 2 cuts. However it doesn’t have an apply button or something to actual apply the subdivide to the face… How do I actually apply the subdivision?
Please always supply an example .blend file with any support question - unless you want to turn this into a tiring and possiby pointless guessing game.
I’d guess (see above) the top face of your cylinder is an n-gon (face with more than 4 vertices), yes?
Subdividing splits every quad (face with 4 vertices) into 4 smaller quads and every triangle (face with 3 vertices) into 4 smaller triangles. But any n-gon will stay an n-gon and just the perimeter edges will be subdivided.
To apply a subdivision you need to be in ‘Object Mode’.
to add a couple of extra verts enter Edit Mode and select edge select (press Ctrl+Tab if your unsure). then hover the mouse over an edge and try “Ctrl+R”
or
select the face at the top of the cylinder,
Press X then F
Re select the edges that made up the top face (edge select mode and hold down alt)
press E then S and scale the edge to about half way (LMB)
Press E
Press Esc
Press Alt+M
Press A