let say u hav to sign up for world community grid(wcg)
then go to wcg website and go to signup page (
World Community Grid - Register)
register your self there and then open your BOINC client
as this is your first run it will show you a list of projects ,scroll down to wcg and click next then enter your user name and password and u are ready to go
if it doesn't show the list of projects and it is a small rectangular window then switch to advanced view and in Tools click Attach to a project or account manager, then select attach to project and then a list of projects come ,do as mentioned earlier.
(if you have to use your computer for any other project then go that projects site and register and do as above)
in the advanced view go to the Advanced -> Preferences and select the processor usage as per your needs
my Preferences screenshot
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