✔ 最佳答案
For your composition, you have to use past tense because you are talking about something happened already.
----
Today is Chung Yang Festival. This morning when we woke up mother said she had to go to Yuen Long (for what ?? ). After mother returned from Yuen Long, my auntie and uncle came to our home already. Then we went up to the mountain together. When we arrived the mountain, we started (to do what???- I think you are talking about sweeping of the tomb, so I changed for you) to sweep the tomb. After we finished we went together back home. We had some meals when we arrived home, then we watched TV unil 7 p.m. Then we went to Yuen Long for dinner. After dinner we all went home.