Unlink objects (noob)

I have a problem i am still a beginner in this and i wanted to make a crypt.The problem is that my crypt and my crypt cover now are linked,i mean when i try to select one ,they both select.http://imageshack.us/photo/my-images/827/tombj.jpg

You can put the mesh into edit mode and press the P-KEY while your mouse is over the 3D viewport. Choose Separate By Loose Parts.

And if the verts have become welded, simply reselect the cover verts, then press P - separate by selected. Explore the options available with the p key is edit mode. Very useful.

Welcome to the forums.

Thank you .one more thing i have subdivided the a face of the crypt in more division ,but when i am trying to subdivide a division ,the one next to it ,subdivides to middle and it messes it up.Look at the SShttp://imageshack.us/photo/my-images/545/subdivide.jpg/

Do you have a blender build with b mesh? It should do the trick. B mesh is different when sub surfed and other things.

I have applied a modifier.subdision modifier.I do not know what you mean.