How do I form the present subjunctive?

For regular verbs, the present subjunctive is formed differently depending on whether the verb ends with -ar or -er/ir. For -ar verbs , take the first person singular of the present tense of the verb, remove the -o ending, and add the endings -e, -es, -e, -emos, -éis, -en. For example the verb cantar (to sing) would be conjugated as cante, cantes, cante, cantemos, cantéis, canten.For -er/ir verbs, it is the same structure but with different endings. Take the first person singular of the present tense of the verb, remove the -o ending and add the endings -a, -as, -a, -amos, -áis, -an. For example the verb vivir (to live) would be conjugated as viva, vivas, viva, vivamos, viváis, vivan.There are also some irregular verbs that do not follow the same formation as above.