Working with the Clipboard in the Sequencer
Working with the clipboard in the Sequence Editor is much like doing the same in any other windows application:

To make a selection:

Either Drag the mouse over an area, or hold shift and use the arrow keys.

To copy the selection:

Either press CTRL-C or select "Copy" from the Right-Click pop-up menu.

To cut the selection:

Either press CTRL-X or select "Cut" from the Right-Click pop-up menu.

To Paste the selection

Either press CTRL-V or select "Paste" from the Right-Click pop-up menu.
Note: when using the clipboard, rather look at it this way: while cutting, copying or pasting you don't actually modify the bars of the sequence itsself, but the contents of the bars.