To add users or groups to the Permissions list
Open Registry Editor. 
Click the key whose Permissions list you want to change. 
On the Edit menu, click Permissions, and then click Add. 
In the Select Users, Computers, or Groups dialog box, in Locations, click the computer or domain of the users and groups you want to view. 
Click the name of the user or group, click Add, and then click OK. 
In the Permissions dialog box, under Permissions for name, assign a type of access to the selected user or group as follows: 
To grant the user permission to read the key contents but not to save any changes made to it, select the Allow check box for Read. 
To grant the user permission to open, edit, and take ownership of the selected key, select the Allow check box for Full Control. 
 Caution

Incorrectly editing the registry may severely damage your system. Before making changes to the registry, you should back up any valued data on your computer. 
 Notes

To open Registry Editor, click Start, click Run, type regedit, and then click OK. 
If the check boxes under Permissions are shaded, the key has inherited permissions from the parent object key. 
To allow permissions assigned to a parent key to apply to its subkeys also, click Advanced, and select the Allow inheritable permissions from parent to propagate to this object check box. 
In the Select Users, Computers, or Groups dialog box, if you type the name, rather than selecting it, click Check Names before clicking OK.