See all those dots along the centre edge. The dots indicate faces but the faces don’t show. This you need to fix or they’ll cause problems later on.
Select all the vertices and remove any doubles (W / remove doubles). Go to your mesh and move some of those vertices to check you don’t have any faces where you don’t want them.
for selecting the top faces you could go to the top view (numpad 7) and box select the faces.
For further help please ALWAYS supply a link to your blend file so other people are able to see what you can see
I cannot simply box-select them in top view, because the middle row of verticies is a bit more outside, so selecting in top view would select them as well. :no:
It’s worth remembering that if you have some group of vertices you might want to select several times and are a pain to select, you can save them as a Vertex Group for future use.
His a fairly quick way. You have a face ring around the top of the board so. Select faces and right alt click a perpendicular edge with in the loop. This will select the loop. Now that you have a clean edge selection go to the top view and hit the C key. This will allow you to paint the rest of the selection. You can adjust the selection Brush with the mouse scroll wheel.
To select just the top you could select bordering edge loop with alt+RMB, it goes all the way around. Then select loop inner region from the select menu to select everything inside which selects everything on top.
I should add this tip.
After Selecting a loop, ctrl+E / create a seam. It is useful when going for UV unwrapping. However, having seams, you can just hover on this region and hit L, selects the surrounded by seam region. You may find it useful.
