The imperative of sciō is scītō in the singular and scītōte in the future. These are the future forms, but they are used in the present tense.
Even if you’re a whiz and you know that already, it might be a little less where how to use this imperative in a Latin sentence. The Romans don’t appear to have ordered others to do things like ‘know these by heart before Friday’s exam.’ Instead, the imperative of ‘know’ was more often something like ‘rest assured’ or ‘recall,’ confirming or searching for what is already known rather than standing for the imperative ‘learn.’
Scītōte vobīs semper deum propitium esse, sī bonīs: Know that the god will always favor you, so long as you are good.
Scītō tibi gratiās dābō: trust that I will return the favor.
Scītō exemplum tuī patris: recall the example of your father.
This is also true of habeō, where it means understand, and mēminī.
Habētō tibi me nōn irātum esse: realize that I am not angry with you.
Habetōte vostrum finem: know your limits.
Mementō ora candentia parentis: recall your mother’s glowing features.
From the examples in Lewis and Short, I cannot be sure, but it appears that the imperatives of sciō will always take a direct object or an infinitive construction, and never the dē + ablative construction that may appear with other moods of sciō.