Xojo vs. VB.NET

In vb.net we have Module.vb where I write the open database in XOJO where is this form

There isn’t such a thing
You can create a global module though

However I’d encourage you to not try & write VB.Net in Xojo

thanks , can you give a tip how to create a global module or reference book…

Menu -> Insert -> Module

I program in both Xojo and VB.net most days. On a general level concepts apply both ways.

I would highly recommend you go to http://documentation.xojo.com/ and read the Introduction to Programming with Xojo. It will give you a good grounding in how things work in Xojo.