How do I properly precomile and redeploy these pre-existing websites?

I have three pre-existing websites on our server.  I need to make changes to these websites.  I am not too familiar with precompilation, and these three sites seem to have all been precompiled differently.  Please let me know what I must do to decompile/access the codebehind files, make changes to the websites,  precompile again, and redeploy.  Thank you!  

Website1
- Does not have codebehind (.vb) files
- Does not have a solution file
- Does not have an App_Code folder
- Does not have project files
- Has a Global.asax file
- Does not have a PrecompiledApp.config file
- Has the following in the bin:  Project1.pdb, Project1.xml, Project1.dll, Project2.pdb, Project2.xml, Project2.dll

Website2
- Does not have codebehind (.cs) files
- Has a solution file
- Does not have an App_Code folder
- Does not have a project file
- Does not have a Global.asax file
- Has a PrecompiledApp.config file
- Has the following in the bin:  App_Code.compiled, App_Code.dll, App_Global.asax.compiled, App_Global.asax.dll

Website3
- Has codebehind (.cs) files
- Has a solution file
- Does not have an App_Code folder
- Does not have a project file
- Has a Global.asax file
- Has a PrecompiledApp.config file
- Has the following in the bin:  App_Code.compiled, App_Code.dll, App_Global.asax.compiled, App_Global.asax