Wah How to use "Need"

Need is used when you want to say something necessary to do or to have.
I need to do it = I must do it.

Affirmative           
     I need to go now. (It's necessary to go now.)

Negative
     Today is Saturday, I don't need to go to school. 
     or I needn't go to school.

Interrogative
      Does she need to have the description for buying medicine?  
     or Need she have the description for buying medicine? 

The modal use of 'need' is restricted to its present tense-form. To refer to the past you have to use..

Wah How to use "Need / Want + Gerund (ing)"

To talk about jobs that someone needs to do, you can use need / want + gerund.

• The grass needs cutting. (Someone needs to cut the grass.)
• These windows need cleaning. (These windows need to be cleaned.)
• Her hair looks like it wants washing.
• This carpet wants cleaning.
• I think it will rain soon, the windows want closing now.

In informal British English, want + ing is commonly used, whereas need + ing is more widely used in standard British English.