Here are spells you will need to know for the Wizarding World:

accio- summons things
Alohomora- Opens locked objects
Aparecium- Reveals invisible ink
Avada Kadavra- Murders opponent (Unforgivable)
Avifors- Turns small objects into birds.
Avis- Launches birds from your wand
-- -- --
Crucio- Tortures opponent (Unforgivable)
Confundus- Used to confuse opponent
Conjunctivitis- Damages opponents eyesight
-- -- --
Deletrius- Counters "Prior Incatato"
Densaugeo- Enlarges Teeth
Diffindo- Splits seams
Dissendium- Opens "One eyed witch" hump (in Hogwarts)
-- -- --
Engorgio- Enlarges and item
Ennervate- Counters Stupefy
Expecto Patronum- Creates a Patronus
Expelliarmus- Disarms your opponent
-- -- --
Ferula- Creates bandages
Fidelius- Hides a secret within someone
Finite Incantatum- Stops any current spells
Flipendo- Knocks an object backwards
Furnunculus- Produces boils on opponent
-- -- --
Homorphus- Lockhart's Werewolf "cure"
-- -- --
Impedimenta- Slows an advancing object
Imperio- Controls a person (unforgivable)
Impervius- Makes an object repel water
Incendio- Starts a fire
-- -- --
Locomotor Mortis- Locks opponents legs
Lumos- Creates light at wand tip
-- -- --
Mobiliarbus- Moves objects with wand
Mobilicorpus- Moves unconcious bodies
Morsmorde- Conjures the Dark Mark
-- -- --
Nox- Counter to Lumos
-- -- --
Obliviate- Erases memories
Orchideous- Conjures a bunch of flowers
-- -- --
Petrificus Totalus- Spell Body - Bind
Point Me Charm- Wand acts like a compass
Priori Incantatum- Spell Result when brother wands duel
Prior Incantato- Spell Reveals a wands last spell / cast
-- -- --
Quietus- Counter spell for Sonorus
-- -- --
Reducio- Returns items to original size. Counters Engorgio
Reducto- Blasts solid objects aside
Relashio- releases user from binding
Rictusempra- tickles opponent
Riddikulus- Use this spell and laugh to defeat a boggart
-- -- --
Scruge- Destroys ectoplasm (remains of ghosts)
Serpensortia- Produces Snake
Sonorus- Amplifies voice
Stupefy- Knocks out opponent
-- -- --
Tarantallegra- Forces opponent to dance
-- -- --
Waddiwasi- Unsticks an object
Wingardium Leviosa- Makes on object fly

Unforgivables are curses that are considered too evil to use. Anyone who is caught, and has used an unforgiveable, earns themselves a livetime in Azkaban.