Hi Dan,
Thanks for your inputs.

Here is the code which I used for this
-------------------------------------------------------------------------------
//STEP 1:Initialized MAPI libraries
hr_p = MAPIInitialize (NULL);

//STEP 2: logon to MAPI for enumerating Public Folders
hr = MAPILogonEx(0, "MS Exchange Settings", NULL,
          MAPI_LOGON_UI | MAPI_NEW_SESSION |  MAPI_EXPLICIT_PROFILE ,
          &lpSess);

//STEP 3:Open the MAPI Public Folder store using the IMAPISession
interface
hr_p = HrOpenExchangePublicStore(pSession, &pmdbPublicACL);

//STEP 4: check if its got opened properly using HrGetOneProp
hRes = HrGetOneProp(
        pmdbPublicACL,
        PR_DISPLAY_NAME,
        &tmp);
        if (FAILED(hRes))
            printf("failed hRes");

        printf("I managed to open the folder '%s'\n",tmp->Value.lpszA);
            //result got is : I managed to open the folder 'Public Folders'

//STEP 5: open the MAPI Public Folder tree
hr_p = HrOpenExchangePublicFolders (pmdbPublicACL, &pRoot);

//STEP 6: check if its got opened properly using HrGetOneProp
hRes = HrGetOneProp(
        pRoot,
        PR_DISPLAY_NAME,
        &tmp);
        if (FAILED(hRes))
            printf("failed hRes for public folder");

          printf("I managed to open the folder '%s'\n",tmp->Value.lpszA);
            //result got is :I managed to open the folder 'All Public Folders'

//STEP 7: get Public folder HierarchyTable using GetHierarchyTable
hr_dir = MAPICALL( pRoot)->GetHierarchyTable( MAPI_DEFERRED_ERRORS,
&lpTable);

//STEP 8: Get the list of public folders using HrQueryAllRows
hr_dir = HrQueryAllRows( lpTable, (LPSPropTagArray)&rgColProps, NULL,
NULL, 0L, &lpRow);

//STEP 9: Use FOR loop iterate and print name and size
      for(j = 0; j < lpRow->cRows; j++)
      {
        LPSPropValue lpDNspv_n = PpropFindProp(
                               lpRow->aRow[j].lpProps,
                               lpRow->aRow[j].cValues,
                               PR_DISPLAY_NAME );
        printf("Display Name for pub_fold: '%s'\n", lpDNspv_n->Value.lpszA);
        //result got is :Display Name for pub_fold: 'Internet Newsgroups'
                Display Name for pub_fold: 'public_folder_1'
                Display Name for pub_fold: 'public_folder_2'

        /* As you said in mailchain, I need to use
        LPSPropValue ppvTemp;
        HrGetOneProp(pProp, PR_MESSAGE_SIZE, &ppvTemp);
        to get size of each public folder. But not getting what should I
specify pProp value.
        */
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Similer way I did for getting mailbox size property and there also as
you said I used HrGetOneProp to get size value. But there to use this
function, first I used "HrMailboxLogon" to get "lpUserMDB" which can be
used as pProp value to fetch mailbox size.
Ex:
                hr = HrMailboxLogon(
                    lpMAPISession,
                    lpMDB,
                    pszServerDN,
                    lpspv->Value.lpszA,
                    &lpUserMDB);

and then I sued HrGetOneProp to get size
Ex:
                                                                 hr =
HrGetOneProp(
                    lpUserMDB,
                    PR_MESSAGE_SIZE,
                    &lpProp);

printf("Total Message Size = %d\n",lpProp->Value.l);

Similer way not getting how to use it for PublicFolders.
Please let me know your views on this.

Regards,
Shivaraj