It's really good to use different tenses in your writing for French because this helps the examiner to give you higher marks. I think that the future tense is one of the easiest to learn so it's definietly a good one to try and get under your belt! In French there are two ways to make up the future tense, we call them the 'immediate futre' and the 'simple future'. Today we'll just tackle the 'simple future' tense and once we've got that down we'll do the 'immediate future' another session.
To make the 'simple future', you first take the infinitive of the verb.The 'infinitive' just means the full, unmodified verb, as you would find it in the dictionary, for example, 'manger' (to eat). Once you've got that, you leave it exactly as it is, and then add on the appropriate simple future ending, to match with the subject (the person/object that is doing the verb). The endings are as follows:
Je infinitive+ai
Tu infinitive +as
ll/elle/on infinitive +a
Nous infinitive +ons
Vous infinitive +ez
lls/elles infinitive +ont
So, using the example of the verb 'manger' we can see that putting in the simple future tense would look like this:
Je mangerai, Tu mangeras, Il/Elle/On mangera, Nous mangerons, Vous mangerez, Ils/Elles mangeront.
Now we can write a full sentence using the simple future: "Je mangerai la pomme plus tard." (I will eat the apple later) And that's it, very simple! Do you think you understand? Why don't you try with the verb 'finir' (to finish)?