Here are the highlighted words or phrases that need repair in each sentence:

1. **boarding** - The phrase should be "board games" instead of "boarding games."

2. **playing** - The correct phrasing should be "playing horse riding" should be revised to either "horse riding" or "riding horses" to clarify the activity.

3. **on** - The correct preposition should be "with" instead of "on," making it "learning how to play the guitar with his elder brother."

4. **to get** - The phrase "to get" could be clearer as "to secure" or simply "for" may not be strictly wrong but could be reworded for clarity.

5. **doing** - The sentence would be clearer with "doing it" changed to "listening to it," making it consistent with the earlier part of the sentence.

6. **like do** - The correct formatting should be "like to do" instead of "like do."

Based on these points, the highlighted words needing repair are:
1. **boarding**
2. **playing**
3. **on**
4. **to get**
5. **doing**
6. **like**