The lesson you have linked is about using the present tense for near and immediate future events - this is not a separate or compound tense and there is no auxiliary verb used. 

In contrast to present tense, passé composé and other compound tenses, require auxiliaries which will be either avoir or être. 

In compound tenses, there is a limited number of verbs that use the auxiliary ‘être’ , with the rest using avoir. Of course, being French and grammar, there are a few verb exceptions that use either être or avoir depending on context (meaning). 

(Also note that  the specific ‘futur proche’ form is different, using ‘aller’ in an ‘auxiliary’ manner).

Stick with the basics initially, and you will learn the exceptions as you go along.

The link gives introductory information to ‘être’ verbs. Over time you will learn the verbs and their auxiliary in compound tenses - both through various specific lessons here, and through general exposure. 

https://progress.lawlessfrench.com/revision/glossary/verb-conjugation-group/verbs-taking-etre-as-auxiliary