RE: Added Form is not visible.
You need to check the window mode in Alternative\modified window if you only modified any GP standard windows.
If you created a new forms/windows in dexterity, then you need to add this new forms/windows to either any modules menu list with using dexterity coding or add it manually in GP home page navigation list.
Have you added your new form to any series like as cards-->sales-->customer contract?
To add you new form/window to GP menu list using dexterity code, have a look on the below link.
blogs.msdn.com/.../quick-tip-getting-command-based-menus-working-in-dexterity.aspx
To add your new form/window to GP home page navigation list, follow below steps.
1. Go to GP home page then right click from the left side of your dynamics GP home.
2. Select Add-->New window.
3. Then select your new from the product which you have created from the chunk file.
4. Click Add and Done to add your new form/window to GP home page navigation list area.
Hope this helps!!!