Fileiopermission In C# Webapplication Where I Have To Give Permission?

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C#

ASP.NET4

Hello
I make a dynamic data website.
In this i am fetching a Problem while Uploading a Image File.
and Give me Error at FileInfo or File Class only at Runtime.

Error is Something Like this..

System.Security.SecurityException: Request for the permission of type 'System.Security.Permissions.FileIOPermission, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.
   at System.Security.CodeAccessSecurityEngine.Check(Object demand, StackCrawlMark& stackMark, Boolean isPermSet)
   at System.Security.CodeAccessSecurityEngine.Check(CodeAccessPermission cap, StackCrawlMark& stackMark)
   at System.Security.CodeAccessPermission.Demand()
   at System.IO.FileInfo.Init(String fileName, Boolean checkHost)
   at System.IO.FileInfo..ctor(String fileName)
   at Product.btnSave_Click(Object sender, EventArgs e)
The action that failed was:
Demand
The type of the first permission that failed was:
System.Security.Permissions.FileIOPermission
The Zone of the assembly that failed was:
MyComputer

Please help me out from this error..
Where i have to give Permission, in My Code or Server Side?
And also suggest me what type of permission i have to give..

Waiting best solution from all of my dear Friends.
Thanks.