1. Determining whether a word is a verb is simple. All Spanish verbs will end in ‘-ar’, ‘-er’, or ‘-ir’.2. Determine the subject of the verb. Who is doing the verb.3. Determine whether the verb is an -ir, -ar or -er verb. 4. Remove the last two letters, but remember what the letter before the r was. That part of the verb is the stem.5. Add one of the following, depending on the subject and ending of the verb. Use the rules when changing the last two letters for regular verbs.