Affirmative and negatives command
You need to go to now.
2 Answers
You need to go now is not a direct command, it is a statement that implies something.
"Go now" would be an affirmative command.
"Don't go now" would be a negative command.
In the informal:
The first might be: Necesitas irte ahora mismo
Although I am never quite sure where "tener que" is favored over "necesitar", nor where one might choose "salir" over "irse"
The affirmative command might be:
" ¡Vete ahora!"
The negative:
" ¡No te vayas ahora!"
Beyond this it is not clear to me what you are asking for.
Bosque is quite right, I guess it would be possible to use the imperative if you said something like ... 'es necesario que' + se vaya ahorita. But for some reason I prefer 'tiene que irse' or 'necesita irse' etc.
If you'd like to review how to use the imperative (command firm) this might help Pongámos Mandones - Lets get Bossy