Down the stretch we go!
All the tricky parts are behind us. Its time to stretch the base upward a bit.

Hit (toggle) A to De-select all vertices.
Hit -minus on the number pad a few times to zoom out.
Hit B and box select all vertices on top of the bottom base.
Hit E to extrude.
Hit Z to stay on the z plane.
Hold in Ctrl move the mouse to extrude up once or 1.0000 on the global Z.
Hit Enter. See image.
Repeat the last four steps about seven times, or however tall you want the column.

Joining and Topping it off!
Now the only thing left to do is connect the top base to the column body that you just created.

Hit (toggle) Tab to get to Object mode.
Hit -minus on the number pad to zoom out until you see both the column and top base you created and moved up earlier.
Right mouse click on the top base.
Hold Shift and Right mouse click on the column.
You should now only have the two objects selected.
Hit Ctrl-J join selected meshes.
Hit (toggle) Tab to get to Edit mode.
Hit (toggle) A to De-select all vertices.
Hit B and box select all vertices of the top base. see image.

Hit G to grab the base
Hit Z to stay on the z plane.
Move your mouse down until you line up the bottom vertices from the top base with the top vertices of the bottom column. Enter. See image.

Hit (toggle) A to De-select all vertices.
Hit B and box select the two sets of vertices that you just lined up.
There should be 64 all together.
Click the Remove doubles from the Mesh tools panel. See image.

Now Tab into Object mode and look at your work. One final thing. If your column looks like it has a black line where the pieces came together. You need to recalculate the normals.
Hit (toggle) Tab to get to Edit mode.
Hit (toggle) A to Select all vertices.
Hit Ctrl-N recalculate normals outside.

Tada! Now its up to you to do whatever you like with your new column. I hope you found this tutorial helpful.