How to Ride the Metro?

Hi, I’m new to Houston, just working here for a month or two. I have been using the Metro bus system to get around because I have no vehicle here. I use the Metro’s apps, but I’m pretty confused with all of the transferring between buses and bus stations and walking in between. Two days ago my bus went completely off course while the driver parked at a Walgreens to go get snacks?! After 20 minutes she came back on the bus and I had to completely reroute. I’m new to Houston and to large cities in general, and the bus system has me very confused. Any help and tips would be appreciated, thank you!