The error indicates perhaps an issue with the web.config file at that location:

C:Program Files (x86)K2 blackpearlWebServicesIdentity

Do you have an environment in which this is working?  Perhaps comparing the web.config file to see if there are any strange differences.

URL at highlight is own computer, Bacuse i install k2 on own computer.  I want to change url to server name. Help me please. T_T

Check the [Identity].[ClaimIssuer] table on your K2 database. You should have at least 2 entries listed. Are both showing the correct URL? The one that is pointing to your K2 server?