Try making the negative past simple - be careful, the most common mistake is to use the simple past form after 'didn't' when you should use the infinitive (for example: 'I didn't went' instead of 'I didn't go'). Even quite experienced students do this, so it's a good idea to practise this form until it's automatic.
Click here to review how to make the English past simple.
Click here to download this exercise in PDF (with answers)
If you want to learn more about the tenses, especially about how to use them when you're speaking, you could try my video course, Terrific Tenses, which is part of Perfect English Grammar Plus.