Is this for internal use or external? VLANing is simple separating off subnets which can be used to place different devices on and cut on or off routing for said subnet.
For example. I can use 192.168.1.1 vlan 1 as my production subnet where I keep all my internal devices and 192.168.2.1 on vlan 10 as another subnet I could use to host a website, then I could block communications between vlan 1 and vlan 10 so I can only access vlan 10 from the outside. (which can be done quite a few ways, either switch level with access ports or via firewall and blocking access rules).
Long story short. I dont think you are really looking for vlaning as a solution. It wont do anything for what you need since accessing a TOR based site is an external link which refers to your public IP from ISP... it wont be protected and will give away your location. You would need to mask it with a VPN or something which still isn't secure on an ISP level.
This is also why TOR isnt secure... its even on their website. End points are not protected so if someone wanted too, they could see the end point of the packets. Only thing protected in nodes in between where data is transmitted... This is why many people have moved away from using Tor long time ago. Just an FYI.
https://www.torproject.org/about/overview.html.en#stayinganonymous