1. To give an affirmative or negative command in the Ud or Uds. forma, use the present-tense yo form as the stem just as you did for negative tú commands and add -e or -en for -ar verbs and -a or -an for -er/ir verbs.
cortar corto Señor, corte las chuletas de cerdo
probar pruebo Señores, prueben la carne asada
perder pierdo No pierdan Uds. los fósforos
servir sirvo Señorita, sirva la ensalada.
2. Affirmative and negative Ud and Uds. commands have the same spelling changes and irregular forms as negative tú commands.
3. The same rules you know for tu commands regarding pronouns apply to Ud. and Uds. commands as well. Attach pronouns to affirmative commands and place pronouns right before the verb with negative commands.
¿Dónde ponemos la leña?
Pónganla en un lugar seco
¿Encendemos la fogata ahora?
No, no la enciendan todavía