Don’t say: 
– He don’t like pizza.
– She don’t want to go.
– It don’t work.
– Maria don’t understand.

Say this:
– He doesn’t like pizza.
– She doesn’t want to go.
– It doesn’t work.
– Maria doesn’t understand.

Remember:

• I don’t; You don’t; We don’t; They don’t
• He doesn’t; She doesn’t; It doesn’t
•  Don’t = do not
•  Doesn’t = does not

– Victor doesn’t know how to dance.
– My dog doesn’t feel well.

• A website with more information
• A practice test
• A Youtube video (English/Spanish)