Verbs do not translate litterally so there is no exact match for those verb tense in English. It's a subject that would need more than few sentence to answe it properly. The short answer is: "présent" is for what is happening now, "passé composé" and "imparfait" are both for past actions (at this stage, only remember that "passé composé" is more used and "imparfait" more tricky), "futur" is for (obviously) future ones. You may also want to learn conditionnel ("would") but I would not bother with "plus-que-parfait" and "passé simple". "Subjonctif présent" would be more useful yet quite advanced so I'd keep it for much later.

To complete this answer, I can tell you the difference between "imparfait/passé composé" and "passé simple" is that "imparfait" and "passé composé" are used for description, or for habits. While "passé simple" is used to describe actions. All of these happening in the past. Basically, "plus-que-parfait" is "past perfect" : j'avais mangé / I had eaten. "Subjonctif présent" is more complex to explain, but it happens with embedded sentences such as "Il faut QUE j'aille (subjonctive of aller) / I need TO go", the preposition que often induces the subjonctive. And more specifically, in a construction that has nothing in common with english : "I want you TO do... / je veux QUE tu fasses"