Here is the sample code to get the list of reports in a tree structure, before this you need to add the web reference to your reporting server's web service, a sample url will loook like this:
http:///reportserver/reportservice2005.asmx
Here is the sample code.
Public Shared Function GetReportsNode(ByVal pUserName As String, ByVal pPassword As String, ByVal pDomain As String) As TreeNode
Dim _reportRoot As TreeNode
Dim _report As TreeNode
Dim _folder As TreeNode
Dim _condition As reportservice2005.SearchCondition
Dim _conditions(0) As reportservice2005.SearchCondition
Dim _cReports As reportservice2005.CatalogItem()
Dim _cItems As reportservice2005.CatalogItem()
Dim _rp As reportservice2005.ReportingService2005 = New reportservice2005.ReportingService2005()
'Pass login credentils to SSRS
_rp.Credentials = New System.Net.NetworkCredential(pUserName, pPassword, pDomain)
'_rp.Credentials = System.Net.CredentialCache.DefaultCredentials
'Get the list of all items
_cItems = _rp.ListChildren("/", True)
_reportRoot = New TreeNode("Reports")
_reportRoot.NavigateUrl = "#"
For Each _cItem As reportservice2005.CatalogItem In _cItems
If _cItem.Type = reportservice2005.ItemTypeEnum.Folder Then
_condition = New reportservice2005.SearchCondition
'Build the condition object to get all the reports from a folder, by setting Report property "Name" to empty
_condition.Condition = reportservice2005.ConditionEnum.Contains
_condition.ConditionSpecified = True
_condition.Name = "Name"
_condition.Value = ""
_conditions(0) = _condition
_folder = New TreeNode(_cItem.Name)
'Find all the items inside a given folder.
_cReports = _rp.FindItems(_cItem.Path, reportservice2005.BooleanOperatorEnum.Or, _conditions)
'loop through each item and create the tree structure
For Each _cReport As reportservice2005.CatalogItem In _cReports
_report = New TreeNode(_cReport.Name)
_report.NavigateUrl = "Reports/Reports.aspx?ReportPath=" & _cReport.Path
_folder.ChildNodes.Add(_report)
Next
_reportRoot.ChildNodes.Add(_folder)
End If
Next
Return _reportRoot
End Function