If the three Julia Chavez meeting records you made in Lab 2a are correct except the Meeting IDs aren't Mgt-01, Mtg-02 and Mtg-03, then the Meeting records you import in Lab 2b will have different numbers than what the instructions say. So you either need to understand how to deal with that while you're following the Lab 2b instructions (see below), or you need to fix the issue now. 

The problem with fixing now is record ID's can NOT be edited/changed so the only way to truly fix this is to delete your Meeting object, along with its exisiting records, and recreate Meeting & those three records again, unfortunately. But it's not really that bad.

If you want to truly fix the problem before going on to Lab 2b then:

1. Click the Setup gear (upper right) and select Setup

2. Click the Object Manager tab and select the Meeting object from the list in the central panel

3. Click the Delete button on the upper right

4. In the popup, click the blue Delete button

5. Now do Steps 55-85 of Lab 2a and stop there

6. Then do Steps 90-113 of Lab 2a

7. Re-grade by using the App Launcher to open the Grader App and follow instructions to run the scoring routine again and then be sure to reload the page to see the updated error list & grade certificate

Alternatively, if you want to just continue on to Lab 2b without doing the steps above, you can but you have to remember–the ten records you import in Lab 2b are supposed to start with Mgt-04. If yours start with Mtg-07, for example, instead, then that is 3 higher so just add 3 whenever the Lab 2b instructions refer to a specific Meeting ID and you'll be fine. For example, if the Lab 2b instructions say something about Mgt-07, then for you it would be Mtg-10, and so on. If you're unsure about that, then do the steps above to fix the issue properly so Lab 2b will work exactly as written.