rigging questions
 

What to do for enlarged joints.
and
What to do for thumb curl ,do we have to make joint for curl from strating or later on.It is too difficult to adjust joint later on.
Please help.
Regards.

Enlarged joints? You can change the size of the displayed joints in the preferences, or in the display menu.

For a finger curl, you would make it straight, then rotate each joint during animation.

What do you mean too difficult to adjust later on? If you mean moving, you can hold 'd' I believe, and move the joint independently of its children. Also, you can enter component mode and rotate the pivot so that it rotates correctly, if that's what you mean.