how do i know what verb to use in a sentence
How do i know when to use -ar or -er in a sentence.
You don't choose a verb because it (or, better, the infinitive) ends in ar/er/ir. You choose based on the meaning fitting what you are trying to say. You may have been given some schoolwork exercise (perhaps to fill in blanks in sentences) where some hint was provided (e.g. choose a verb ending in -ar) but that's no different from the case where the hint was that the verb starts with "m" (or whatever).
You might (as some kind of practice/exercise) attempt to write a paragraph using, say, only verbs that end in -ar but that's a totally artificial situation; similar in spirit to trying to use only words that are five letters long.
you just have to choose a verb that you want in your sentence. It doesnt matter what the ending is.
I don't mean to be rude, but this isn't complicated, ok? I love you mi tierra, and I'm so glad you are here, so we can all learn together, but really, it's not has hard as you are making it, ok? Did you run? Did you walk? Did you talk scream shop look take give smile love hate rob donate work hug rub dance? You have to learn them. And depending on what it is exactly you dd will tell you whether it is ar or er or ir. You have to make them a part of your life, love. If you walk, you have to retrain yourself to know what walk is in spanish. Did you love your chick/bro today? You have to learn that word and retrain your brain. We'll help, but we can't tell you what you did today! Only you know that.
I'm not sure there is enough information in your question to provide you with any help. Your verb will depend entirely on the word you need to use within the context of your sentence and situation.
What are you trying to say or write?