Hola Pat

For a command you need the form of the imperative: poneos

"Os ponéis" is conjugating the verb "ponerse" in the present tense, for example:

But as a command:

You won't find the word poneos in the dictionary because it is a conjugated verb and it has a pronoun attached to it, but you will find the infinitive "ponerse".

I hope this clarified it.

Saludos

Inma

Hola Gail, thanks for contacting us and sorry about our delay. The form "poneos" comes from the reflexive verb "ponerse" in the 2nd person plural ("vosotros"). The original form should be "ponedos" but we need to remove the -d due to phonetical reasons when using the 2nd person plural and pronouns starting by a vowel. I hope that this is clearer now. Gracias! Silvia.