Almost every English verb can be used as an actual, real verb or take the form of a present or past participle. The present or past participle can be used as a modifier, or as an auxillary or helping verb.
English has various verb tenses and moods, and some tenses are expressed with one word, and others with more than one word - which is a form of to be + present or past participle, or a form of to have + past participle. It's best to think of the entire phrase (to be or to have + auxillary/helping verb) as the verb.
Progressive tenses use to be + present participle.
Passive moods use to be + past participle.
Perfect tenses use to have + past participle.
Each of these has a different meaning.
There are also modal auxillaries such as will, would, etc. that express future and conditional tenses.
Long story short: study your tenses!