You really don't 'wanna access & edit'. The Windows registry is not somewhere to be messing about if you have no idea how to even access it (as other posters have already said).
Ok then Thomas, have at it. Don't complain when you completely c0ck everything up though.
I would strongly advise that you locate a website that explains in minute detail how to backup and restore any changes you make before you go any further!
regedit allows you to make changes to your registry.
But as me and others have said, it is a very risky thing to do unless you know what you are doing.
While Microsoft do provide regedit as part of Windows they dont "promote" it and it is really only there for computer specialists to make changes if they really need to.