In any language, when we refer to something happening, we always use a tense to indicate whether it is going to, is, or has already, happened.
Learning French would be much easier if there were no tenses, but communicating something clearly would be impossible - tenses are really powerful.
There are three main types of tenses: present (now), past (then) and future (to be). There are different rules for each, depending on how they're used.
This is tricky stuff, but like most tricky stuff, get somewhere with it and you'll get great marks!