To form familiar commands, regular -ar verbs end in -a, and -er and -ir verbs end in -e for the tú form.
Change the final -r to -d for the vosotros form. Negative familiar commands use the subjunctive
forms, so -ar verbs end in -es and -éis, while -er and -ir verbs end in -as and -áis for the tú and
vosotros forms.
To form formal commands of verbs, drop the -o ending of the yo form, and add the opposite vowel
ending. This means -ar verbs will add -e for the Usted form and -en for the Ustedes form; while -er
and -ir verbs will add -a for Usted and -an for Ustedes. To make a command negative, just add no
before it.
Ir and ser have irregular forms as formal commands: vaya and vayan for ir and sea and sean for ser.
Verbs that end in -car, -gar and -zar have the following changes in commands as well: c becomes qu,
g becomes gu, and z becomes c.