The very best yoga instructors are happy to answer queries about the yoga poses throughout a class so long as you keep it to the very least. It’s OK to ask unless you understand how you have to be positioned; you do not want to harm yourself because you do something wrong. If you simply can’t do a specific pose, such as Lotus, ask, what may i do rather than Lotus? & most instructors will be happy to help you.
If you have more descriptive questions about what poses you can practice in the home to improve a certain series of poses, or even to help open up tight spots such as hips and shoulders, talk to your instructor after the class is over.