Resizing the columns is easy.  Here's how:

1) Move the cursor over a column line in the column title area.  You'll see the cursor change.  In the figure below, look to the right of the column title Category for the cursor.

2) When the cursor changes, hold down on the mouse button and move the column line to a new location.  In the example below, the right side of the column Category is being moved to make the column larger.

3) Release the mouse button.  That's it!