Luckily, the -ta form is just like the -te form: just change the te (or de) to ta (or da).
As you learn Japanese, keep practicing the -ta form, so you can take any Japanese verb and give its -ta form with hesitation. If you spend just a few minutes every day learning Japanese, your language skill will improve quickly. Stick with it, and you will be amazed at how much Japanese you learn!
If you want to learn Japanese online, why not consider online lessons at Nihongo-Pro? Our professional teachers will guide you in private lessons customized just for you, focused on your Japanese learning goal. With excellent teachers, superb lessons, and an unbeatable online Japanese classroom, you can't go wrong learning Japanese at Nihongo-Pro.
We hope to see you in an online Japanese class one day! Until then, we wish you the best of luck and all the success on the JLPT N4 and in all of your Japanese studies.