I’m just going to stick to the real basics of English verb tenses in this posting (no need at this time to muddy the waters with complications like perfect tenses and conditional tenses, etc.).
Keeping matters fundamental, let’s say that English has three basic tenses: past, present and future.
We’ll start with the present with the verb to be. Example: "I am in my living room right now typing on my computer." Here, the present tense of the verb be is am because it is singular first person.
Past tense: "Last night I was in my living room watching the baseball playoffs." Here the first person past single form of be is was.
Future tense: "Tomorrow morning I will be in my living room reading the newspaper." Here the future form is will be.
I actually started with one of the more difficult verbs in English because its form changes depending on whether the subject is singular or plural or first (I, we), second (you, you) or third (he, she, it, they) person.
Most regular verbs are much simpler. They become singular by adding an s at the end and become past tense by adding an ed at the end. Future tense is indicated by adding a will before the verb.
Let’s look at the verb walk: I walk, he walks, they walk. I walked, he walked, they walked. I will walk, he will walk, they will walk.
Fairly straightforward, those, but look at one of the many irregular verbs in English, in this case eat: I eat, he eats, they eat. I ate, he ate, they ate. I will eat, he will eat, they will eat. See how the past tense is irregular.
Unfortunately, in English you have to memorize the irregular verbs in all their forms. Here’s a list to get you started.