Without knowing specifics the best course of actions are
- Errors can come from the settings for Option Strict and Option Infer, the compiler will throw out more errors when coding in old style VB6 than if done as pure VB.NET
- With the Error List window open first look at each error and if there are errors indicating a type can not be found e.g. Are you missing a using directive, tackle these first as in many cases will resolve other issue. Missing a using directive may come from either a developer removed a needed using statement.
- Look at dependencies for a project, are they compatible with the .NET Framework being used in your project
- Scope of variables can lead to errors
Even if the above are helpful or semi-helpful and still have errors, come back here with specifics for each error written out rather than providing screenshot. You can select an error from the error list window copy and paste here.