HOW DO THE TENSES WORK AND HOW DO I KNOW WHEN TO USE THEM?!?!?!!!!?

Don't panic. Just follow this extremely brief summary of all the tenses you'd come across.

Present (présent) : This should be very straightforward, just as in English, francophones use this tense to indicate that an action is occurring in the present. Don't forget to check you're using the correct endings. :) e.g. Je trouve - I find.

Past - passé composé : It's made up of the auxiliary verb (avoir/être) and your past participle. Broadly speaking, this is used to describe what took place exactly and a succession of events. Remember être as the auxiliary goes before any of the DR MRS VAN DER TRAMP verbs. e.g. Les quatre amies sont retournées et elles ont dînés ensemble. 

Past - Imperfect (imparfait) : This is used to describe the background or setting and past habits that are not current habits anymore. e.g. Ils se mangeaient mais maintenant, cela n'est plus le cas.

Conditional (conditionnel) : Should, would, must, might and could are all examples of the conditional in English. You could use it in an if...then... sentence. However, not all of these English verbs do not exist as verbs in French. They have to be conjugated, BUT the good news is that for almost all verbs, all you have to do is add the appropriate 'imperfect' ending to the infinitive. Of course, there are exceptions, but they are the usual: être, avoir, faire, aller etc.

Future : As you'd expect, this tense is used when referring to the future and essentially it's the same as the conditional, but with present avoir added to the end of the infinitive. e.g. Nous présenterons.

Subjunctive (subjonctif) : This follows a que phrase. This phrase 99% of the time will be about wanting something, emotion, doubt, possibility, judgement and necessity. Il est nécessaire que vous y alliez. 

Pluperfect (plus-que-parfait) : Used to refer what happened before the past. For example, you went  to a museum yesterday because the day before that, you saw an ad on TV. It's also used when translating the 'I had done so and so' into French. It is basically the combination of the passé composé and the imparfait. e.g. Tu étais partie quand je suis arrivé.

Imperative (impératif) : This is you requesting/commanding somebody to do something. So, there are only three different types of people relative to yourself that you can order around: you (tu), y'all (vous) and we (nous). So drop the pronoun. If conjugating an -ER verb, drop the -s if the pronoun is tu.