Create the guest account in Active Directory, add them to any groups that you want.
Navigate to the base folder/directory that houses all the folders shared over the network.
Right click -> Properties -> Security
In "Group or User Names" make sure that the guest user, and any of their groups, aren't listed. I generally just include the Administrator group, creator owner and system.
Click Apply then Advanced. Tick "Replace permission entries on all child objects ...". This will copy the security permissions from the base folder/drive you just set to all of the folders inside the base folder/drive. If you have any custom security settings on child drives they will be overwritten.
Then on each folder you want the guest to be able to access ensure the sharing permissions are set to "Everyone", as above, then go to the security tab.
You will need to go into advanced and untick "Allow inheritable permissions from the parent..." to be able to change permissions. Once that's done you can add the guest account to the Security tab with whatever permissions you want.
Anyone who is not a member of the groups added to the base directory/folder will not be able to access the folders unless given permission.