How to lower volume in specific section of track?

[HighMoon]

Hello,
I have a backing track, guitar, in my project. I want to pot the backing track down when my second track, lead guitar, comes in. Then bring it back up after. I can't figure out how to highlight the section, then lower the volume for mix down. 
This is on mobile app. I watched a few vids, but seems like they're desktop examples?? The process isn't matching up.

Have you tried using automation?

I tried playing around with that, but at the time I wasn't having any luck. However, now that you mentioned it here, I went back and tried again. I think I have it now. Definitely on the right track. Thank you!