This is the first tense we learn. It’s confusing at first, but the good news is, that once you have learned the patterns of how you change the endings to ‘fit’ the person, you’ve learned how to change almost every verb!!
To make the verb ‘fit’ the person, you simply take the AR/ER/IR off the full form of the verb, & replace them with something else. I’ve coloured the changes in RED.
The beginning part of the verb tells you what is being done, & the end tells you who is doing it.