Welcome newbies! We’d love for y’all to introduce yourselves in the introductions thread!
First of all, I found some information regarding the question of labels on the wiki here
I recommend practicing new tricks on a throw-away pattern, such as a square. Just in case. Or at least not saving until you know that you’ve got it right, for ease of roll-back. But I recommend saving constantly, because you never know what might happen. So you would need a safe file to risk mutilating beyond comprehension. Unless you want the extra practice anyway! 
If you haven’t done the pattern tracing part of the process which @Sewing4Fun mentioned, you will have to do that first. I’m not clear on if you have already finished that step or not.
- Once that is done, make sure you are in the Detalis view rather than the Draw view.
- In the Details view right-click the pattern piece which you desire to label
- Select “Options”
Now you are in a screen that looks almost exactly like the screen that popped up when you finished tracing the pattern, except that all the juicy options are no longer greyed out.
- Select the Labels tab on the left side of the dialog.
- I recommend filling in the “Name of detail” field with something descriptive of exactly which pattern detail you’re messing with. Then the “Details” tally on the bottom right of the screen will have meaningful information in it.
- Up at the top, right below the tabs, is a button labeled “Edit template” directly to the right of the words “Label template:” click it.
- The “Edit label template” is grey & lifeless, click the mysterious green plus sign.
- Behold! the dialog comes to life! muahahahahem.
- Insert your desired label in the Text: field.
- Experiment with "Insert…"ing scripting which you could add to make the program do the boring work that you will be using repetitiously for you!
- If you added such a script, save the label template to your drive with the suitable button. This will allow you to Import a template rather than having to type it all in for every single pattern piece, which is especially useful if you have multiple lines in your template.
- Click “Okay” to finish working with your template.
- Click the “Labels” tab at the top
- Check the “Detail label visible” box with a click
- Give it a suitable width & height. If a 1 unit square is good, you don’t need to bother about anything. But that’s kinda small, even if you’re using inches.
- but most of all, (make a backup,) “Take chances, make mistakes, get messy!”
But that only works if you’re wanting to label pattern pieces with labels that will print with the layout. If you’re wanting to label multiple specific parts of a single pattern piece, I’m not sure if that’s possible yet.