A closer look
Verb tense is the form a verb takes to show time. Present forms usually talk about now; past forms usually describe finished events.
I walk to school is happening now. I walked to school is already done.
One caution: tense form does not always match the actual time. In Could you help me? the past form talks about right now, just more politely. And a present form can bring the past to life, as in So he walks in and says... when telling a story.