Pulling UserForm Data into Email Module

Hello everyone,

So I am creating a project management tool for my company. The way to create a project involves entering data into a UserForm. Two of the form inputs that I currently am looking at are called "txtAssignedTo" and "txtAssignedBy". I currently have this macro running once the user submits the form:

Sub NewProjectEmailMacro()
'Email workbook to specified users
    Dim wb1 As Workbook
    Dim OutApp As Object
    Dim OutMail As Object

    With Application
        .ScreenUpdating = False
        .EnableEvents = False
    End With

    Set wb1 = ActiveWorkbook

    Set OutApp = CreateObject("Outlook.Application")
    Set OutMail = OutApp.CreateItem(0)

    On Error Resume Next
    With OutMail
        .To = ""
        .CC = ""
        .BCC = ""
        .Subject = "A New Project has been Created"
        .Body = "A new project in the Project Tracker has been created. Please advise."
        .Attachments.Add ActiveWorkbook.FullName
        .Send
    End With
    On Error GoTo 0

    Set OutMail = Nothing
    Set OutApp = Nothing

    With Application
        .ScreenUpdating = True
        .EnableEvents = True
    End With
End Sub

Currently, I am only able to know how to input specific email addresses into the "To" section of the macro. What I am looking to do is somehow be able to input the user values of "txtAssignedTo" and "txtAssignedBy" into the "To" section to send an email to only those two people. Also, I believe I will need to concatenate the final part of the email address (@yahoo.com for example will not be included in the form).

Any help is greatly appreciated and thank you as always!