@ Big Heart, I think it would be helpful if you looked at these explanations: 1 - I played football. This is the past simple.You use this tense to talk about something that happened in a finished period of time : yesterday, last week, ten years ago, in 2012. Maybe you played football once or maybe you played football a hundred times. For example: 'I played football every day when I was a child' . The important thing about the past tense is that the period is finished. You're not a child any more, so you use the past tense. 2 - I have played football. This is the present perfect. You use this form to talk about an unfinished period of time, or an indefinite time in your life. For example: I've played football twice this week. I've played football a lot recently. I've played football a few times since I joined the sports club. Have you ever played football in the snow? No, I haven't. That's the best football match I've played in my life. 3. I had played football. Maria's definition is fine for this one.

I'll add to Maria's answer, because I do not completely agree. 1 - Implies the specific action referred to is finished, completed, or otherwise in the past. Do not confuse this with "once". Pelé played football. Obviously he played in many games. Those are in the past. He may continue to play, but my statement refers only to games in the past. 2- This is more concerned with the experience than the action. That is, if someone asked you "What did you do yesterday?" you would not answer by saying "I have played football." This is because you are referring to the fact that you have experience performing the action and does not refer to the action itself. It also does NOT imply the action is continuing. Again, it refers only to the past, even if I am playing football at this exact moment. In that case, it would refer only to the times in the past I previously played, not the current game I am playing. 3 - This one is very difficult, so I'll expand, but Maria is correct. This is basically saying that, if you could travel back in time to the past to some specific moment, then you could, at that time, make the statement "I played football." It is as if you are saying "In the past of the past, I played football." Again this refers only to action in the past and does not refer to any current action. For example, if the current time is 2:00 pm, I could say, "At 9:00am this morning, I got out of bed and ate breakfast. At 11:00 am, my friend wanted to eat lunch with me, but I had eaten only 2 hours before." So we have three times, the preset (2:00pm), the past (11:00am) and the past of the past (9:00am). I may eat in the near future, I could be eating lunch at the moment I make these statements, or I may have even eaten lunch at 1:00pm (still the past). These things make no difference. Normally the actual time, 9:00am, would not be specified, but something should indicate an event, action, or moment that occurred after the "had" action.

I agree with Maria except for #2. It is indeed past perfect but present perfect does not describe an action that started in the past and continues in the present. That would be present perfect continuous. Present perfect is used to in at least three ways. 1) an action or actions concluded in the past at an unspecified time. "I have played football before." "I have taken that class three times." 2) a state that changes over time. "I have gotten good at pool." 3) to describe things we've accomplished or completed. This could be as recently as this instant. "I have finished my homework." "They have won the contest." Present perfect continuous, as Maria points out, is an action that started in the past and continues into the present. "We have been playing football for three hours. When will we stop?"

Just a couple more points to add to the other great answers... 1. "I played football." This is not a complete sentence. Tell us WHEN this happened. This verb form tells us about the past. 2. "I have played football." This is a complete sentence. It tells us about the present. Basically, we use an event in the past to describe the present situation. I'll use a couple of the above examples: "I have played football before." = I have the experience of playing football. I know how to play football. "I've played football a lot recently. = I am feeling healthier/fitter/exhausted(?) as a result. You will never use "I have played football" when talking about the past. This piece of grammar connects the past to the present. 3. "I had played football." This needs another past event (simple past) to function. We use an even in the earlier past to describe a situation in the (later) past. Using Maria's example, "Before I went to the shop I had played football," this tells me that when you went to the shop, you were still wearing your football gear, or you were covered in mud (from playing football), or you were tired and thirsty... and so on.