Group classes and workshops teach you a series of gentle movements that you can do on a daily basis to increase voluntary control of your muscles, and reduce tension.
In most settings you may want to bring a yoga mat as you will be learning a number of movements on the floor. Wear comfortable, loose-fitting clothes (no jean, dresses, belts), although you won’t be working up a sweat.
If you want to get a sense of what these are like you can try some online resources, such as these:
John Loupos (he is also a tai chi instructor) https://www.youtube.com/watch?v=ZAosTMEwG8I&list=PLyzUujiii1An9m7BemQvrHq3zXyTWWxhL
Esther Ekhart (she is also a yoga instructor) https://www.youtube.com/watch?v=FeJlrUPePLc&list=PL8E3E9CB97FE4D473