See Viv's answer on how to fix your code. But I think I can clear up this mystery for you.

>it said tht it has an error in the line 93 but my code has only 58 lines and it says the error is in the file Navigate.g.vb, but thta file does not exist

It usually does exist you can find it in the \obj\Debug directory. It is the VB code that is being generated by your XAML.

I usually don't touch that file, but it is useful to know that it is there and what created it.