Once you get to grips with them, locks are all part of the fun of a canal holiday – and a most efficient form of exercise!
Most locks have two sets of gates (top and bottom) and a chamber which your boat enters into. Crucially, locks also have openings (or sluice gates) at the top and bottom and it is by opening these that water is allowed into and out of the chamber to raise or lower the water level - and hence the boat. You and your crew will open and close the paddles using a lock handle (or windlass) which you will carry with you on your cruise.
It may help you to visualise the lock as a huge bath with the taps (top sluices) at the higher end and the plug hole (bottom sluices) at the lower. This may remind you not to run the 'taps' when the 'plughole' is open, which would waste water and never allow the lock to fill.