Hola James

The second part of the verb in perfect tenses, e.g. he ido, has comido, habéis venido, habías cantado... is called "past participle" (participio); regular past participles end in -ado or -ido, but there are some that are irregular that have different endings, like hecho, dicho, puesto...

Here is a bit more information, have a look.

I hope that helps.

¡Feliz Año Nuevo!

Inma