I would like to setup 2 wireless connections. One is private and the other is public. And the Public connection can not see or access share folder and the NAS storage. Which router do I need and how do I do it?
If you want a single router you have to look at business routers/access points like those from Cisco. Those are able to run multiple SSIDs on a single device.
With Linksys equipment you'll need at least two routers.
Setup 1 with two routers:
Modem connects to first router. First router connects to second router.
The first router runs the public wireless. The second router runs the private wireless.
Problem: if the first router gets hacked it may be possible to scan the internet traffic of the second router.
Setup 2 with three routers:
Modem connects to first router (no wireless needed). First router connects to second and third routers (both wireless).
The second is public wireless. The third is private wireless.
The first router should be one which allows you to block all incoming traffic to the first router itself from the "public" router, otherwise you still have the same problem as in setup 1 in case the first router gets hacked.
GV has a point but depending on which router you have now will give you a few options. I have set up a few networks with private/public wireless and I simply set them up with what ever WIRED router they are currently using and a WAP54GP because it supports up to 7 SSID's and VLAN trunking. The fact that you can set up WPA or WPA2 on each SSID you want to keep private or leave it open to the public and seperate the networks via the VLAN. This set up has worked for me with a RV082 as the main router. Its just an idea to toss in the mix of options you have.