First you need to rebuild the entire solution. Then you need to visit the /Setup/Default.aspx page to run all the database scripts.
If you are running it in the debugger it will break on all errors and errors are expected until it runs all the setup scripts, if you keep clicking continue on the errors it will eventually redirect to the setup page by itself.
But instead of running in the debugger, its easier and faster to just rebuild the solution, right click the /Default.aspx file in the root of Web and choose view in browser. This will launch it in the VS web server without loading it in the debugger so it won't stop on every error it will just redirect to the setup page after it detects that it needs to run scripts.
Hope that helps,
Joe