Check which worksheets to export as pdf

I am a beginner in Excel VBA but I would like to create a file where I can select certain worksheets by means of a userform with checkboxes. In principle, it is then intended that only the check boxes where the value is true should be exported.

Below I have 2 codes that work well separately from each other but I have not yet been able to get them to work together.

Note: both codes come from the internet.

If possible I would like to write a loop to keep the overview.

the code to export sheets as pdf and put them in a outlook

Sub Saveaspdfandsend1()
Dim xSht As Worksheet
Dim xFileDlg As FileDialog
Dim xFolder As String
Dim xYesorNo, I, xNum As Integer
Dim xOutlookObj As Object
Dim xEmailObj As Object
Dim xUsedRng As Range
Dim xArrShetts As Variant
Dim xPDFNameAddress As String
Dim xStr As String
xArrShetts = Array("test", "Sheet1", "Sheet2") 'Enter the sheet names you will send as pdf files enclosed with quotation marks and separate them with comma. Make sure there is no special characters such as \/:"*<>| in the file name.

For I = 0 To UBound(xArrShetts)
On Error Resume Next
Set xSht = Application.ActiveWorkbook.Worksheets(xArrShetts(I))
If xSht.Name <> xArrShetts(I) Then
MsgBox "Worksheet no found, exit operation:" & vbCrLf & vbCrLf & xArrShetts(I), vbInformation, "Kutools for Excel"
Exit Sub
End If
Next


Set xFileDlg = Application.FileDialog(msoFileDialogFolderPicker)
If xFileDlg.Show = True Then
xFolder = xFileDlg.SelectedItems(1)
Else
MsgBox "You must specify a folder to save the PDF into." & vbCrLf & vbCrLf & "Press OK to exit this macro.", vbCritical, "Must Specify Destination Folder"
Exit Sub
End If
'Check if file already exist
xYesorNo = MsgBox("If same name files exist in the destination folder, number suffix will be added to the file name automatically to distinguish the duplicates" & vbCrLf & vbCrLf & "Click Yes to continue, click No to cancel", _
vbYesNo + vbQuestion, "File Exists")
If xYesorNo <> vbYes Then Exit Sub
For I = 0 To UBound(xArrShetts)
Set xSht = Application.ActiveWorkbook.Worksheets(xArrShetts(I))

xStr = xFolder & "\" & xSht.Name & ".pdf"
xNum = 1
While Not (Dir(xStr, vbDirectory) = vbNullString)
xStr = xFolder & "\" & xSht.Name & "_" & xNum & ".pdf"
xNum = xNum + 1
Wend
Set xUsedRng = xSht.UsedRange
If Application.WorksheetFunction.CountA(xUsedRng.Cells) <> 0 Then
xSht.ExportAsFixedFormat Type:=xlTypePDF, Filename:=xStr, Quality:=xlQualityStandard
Else

End If
xArrShetts(I) = xStr
Next

'Create Outlook email
Set xOutlookObj = CreateObject("Outlook.Application")
Set xEmailObj = xOutlookObj.CreateItem(0)
With xEmailObj
.Display
.To = ""
.CC = ""
.Subject = "????"
For I = 0 To UBound(xArrShetts)
.Attachments.Add xArrShetts(I)
Next
If DisplayEmail = False Then
'.Send
End If
End With
End Sub

the other code i tried I can see which checkbox is checked unfortunately I can't rewrite it so only the checked boxes will be exported to pdf.

Private Sub CommandButton100_Click()

For i = 100 To 113

If UserForm2.Controls("CheckBox" & i).Value = True Then
a = a + 1
End If

Next i

k = 1

For i = 100 To 113

If UserForm2.Controls("CheckBox" & i).Value = True And a = 1 Then
    b = UserForm2.Controls("CheckBox" & i).Caption & "."
ElseIf UserForm2.Controls("CheckBox" & i).Value = True And k <> a Then
    b = b & UserForm2.Controls("CheckBox" & i).Caption & ", "
    k = k + 1
ElseIf UserForm2.Controls("CheckBox" & i).Value = True And k = a Then
    b = b & "and " & UserForm2.Controls("CheckBox" & i).Caption & "."
End If

Next i

MsgBox ("You have selected " & b)

End Sub

Can someone help me please I am struggling for some time now?