Remane and Upload File

 Hi
Can any one tell me, how to rename the file before uploading
file name will be 1,2,3,4,5.....nth Number, When one user upload file, the name would be 1.jpg(image file) for next user 2.jpg and so on...
As users add the files the next file should be the name incremented (++ ) from the last uploaded file
 i am using the below code to upload the file
 
1 //
2
3 HttpPostedFile myFile = filMyFile.PostedFile;
4
5 // Get size of uploaded file
6 int nFileLen = myFile.ContentLength;
7 // Allocate a buffer for reading of the file
8 byte[] myData = new byte ...