For most verbs, in order to form the past tense, you simply add the suffix -ed to the main form of the verb called the infinitive. And to form the regular past participle which can be a verb form or an adjective, you usually keep the past tense form of the verb, that is the infinitive plus the suffix -ed.
This means that the regular simple past and the participle forms of the verb are the same.
Like in this example:
Love (main verb in the present)
loved (simple past formed by adding ed suffix) and
has/have loved ( past participle formed by adding the helping verb has/have and keeping the past tense form of the verb.
However, there are irregular verbs that do not follow the common structure of adding ed when making the past and past participle.
Download the PDF to see the most common irregular past tense verbs and their verb forms, or past participles.