Upload file too big size

Attachment upload file is too large, how to open limit
WorkflowGen 7.5.0
How to deal with it

Server Error in ‘/wfgen’ Application.

Maximum request length exceeded.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Web.HttpException: Maximum request length exceeded.

Source Error: