You can use the mouse to play... try it. Clicking on yourself will usually do the obvious thing you'd like to do, though sometimes you'll have to revert to the keyboard. Some things are easier with the mouse (fishing) and some are easier with the keyboard (fighting).
Each board typically stands alone. You may need some items from other boards to complete it. The trickiest aspect of this can be determining whether you have the right weapons or items to complete the board... it may be difficult or impossible to complete without specific items.
If you save before you manipulate the board, you should be able to work through it without losing a lot of blood. You'll want to explore everything on the board, and ensure that at the end of the puzzle, it's still possible to return the way you came. You may have to restart the board a few times until you determine the best way through.
Learn how to reorder your inventory and put your best weapon at the top of the list. Use “w” to switch to that weapon.
Sometimes you'll need to use or throw an item, then immediately use your weapon. Order your inventory so the key or other item is right after your weapon. Then when you lose it, your inventory will automatically fall back to the previous item... which will be your weapon.
Sometimes, dropping all your unnecessary items can be helpful as well. There are no monsters that will mess with stuff on the ground, so this is safe.
"wielded" means the item is selected in your inventory.
As of 0.7, scenario designers can choose to use ranged weapons that require ammunition. This kind of weapon is marked with an ª symbol in your inventory.
"worn", means the item is selected in your inventory. "eaten", "drunk" or "used" means you have pressed ENTER while the item is selected.
These items are unique and they may or may not appear in a scenario. "wield", means the item is selected in your inventory. "used" means you have pressed ENTER while the item is selected.