In English, people often use the words ‘do’ and ‘does’ to add emphasis or to add confirmation to a sentence so watch out!
The verb changes depending on the subject and the verb tense (past, present etc) it is also followed by the bare infinitive form of the following verb.
Emphasis - E.g. “This website says that learning English is difficult.”
“This website does say that learning English is difficult.”
Confirmation – E.g. “I wanted to go to the cinema.”
“No you didn’t!”
“Yes, I did want to go to the cinema because I wanted to see the new James Bond film!
There is more useful information about this topic on this website.