Download and install BOINC 7.0.28
Make sure to get the 32 bit or 64 bit version based on your hardware.
Create an account and password.
Add a project, you will have to create an account when you add a project. You have to create an account for each account you add. Make sure to use the same username/password/email/country for each account.
Make sure to add yourself to the overclock.net team on each project you add. You will have to goto the home page of the project and login. Goto your account and search for a team, search for overclock.net and then select join team. It can be a little different for each project, but each project has a section where you can join a team.
In the BOINC manager.
goto advanced mode
Activity -> Use GPU always
Activity -> Run always
Activity -> Network activity always available
This will allow you to use the computer and BOINC to communicate and download/crunch work units while you are on the computer.
Go here for more detail Boinc essentials