If you never tried yoga, or have little experience of yoga practice, I suggest you start with group classes.

There are a few ways to take group classes.  Private yoga studios, gyms, recreation centres, and YMCAs all provide group yoga classes.

You may start with YMCA or recreation centre classes.  These are usually very affordable.  The classes are not hard, very easy to start with.

After a few months' exercise, if you think such classes are not challenging enough for you, you may switch to a private yoga studio.  Many studios provide big discount for the first month.  You may try different studios for a few month, and decide which one fits you the best.