Android Question How to convert this code to b4a

Sub Btnsubmit_Click
      
    Dim oldphone As String = phone.Text
    If phone.Text.StartsWith("0")  Then
        Dim str As String = phone.Text
        str = "256" & str.SubString(1)
        phone.Text = str
    End If
                
    Dim Subscriptiondetails As Map
    Subscriptiondetails.Initialize
    
    Subscriptiondetails.put("username","5")
    Subscriptiondetails.put("password", "ty3")
    Subscriptiondetails.put("api",depositmobilemoney)
    Subscriptiondetails.put("msisdn",phone.Text)
    Subscriptiondetails.put("amount",10000)
    Subscriptiondetails.put("narration",Subscription)
    Subscriptiondetails.put("reference",sbscr)
    Subscriptiondetails.put("status_notification_url","http://108.175.14.205/SMISApi/api/smis/subscriptionresponse")
        
    'Depends on json library
    Dim json As JSONGenerator
    json.Initialize(Subscriptiondetails)
    Dim content As String = json.ToString
        
    'Depends on okHttputils library
    Dim client As HttpJob
    client.Initialize("",Me)
        
    client.PostString("https://payments-dev.blink.co.ug/api/",content)
    client.GetRequest.SetContentType("application/json")    'set the header as json
    client.GetRequest.SetContentEncoding("UTF8")        'set encoding as utf8
        
    Wait For Jobdone(client As HttpJob)
    
    If client.Success Then
        Dim result As String = client.GetString
        Dim data As JSONParser
        data.Initialize(result)   
        
        Dim product As Map = data.NextObject    'I suspect the response is a json object
        
        Dim y As String = product.Get("status")
        Dim z As String = product.Get("error")
        Dim w As  String = product.Get("reference_code")
        
        If y = "PENDING" And z = "false" Then
            MsgboxAsync("Hey!, Yr subscription IS BEING WORKED UPON THANK YOU","Alright")
        End If
        
    End If

      
End Sub