Where can I find and how do I insert Vocal sync ?

First of all, VocalSync is Platinum only. It's a region FX, so you'll open it the same way you open Melodyne (and V-Vocal, if it's still installed on your system). Four things to remember:
 

• VocalSync is optimized for vocals. I haven't had much success aligning non-vocal instruments, like bass to kick or whatever. 
• You need to specify a guide track, which the VocalSync track references for its alignment.
• The preview mode is lo-fi. After alignment, you need to render the clip by bouncing it to itself (like you do with AudioSnap).
• Turning up the dial all the way doesn't necessarily mean tightest alignment. The "sweet spot" can occur anywhere along the dial - it depends on the material. The graphic interface is very helpful in this respect.

https://youtu.be/ao-wFsWI7qE

So I panned them all the way left and right 100% (because it sounded better). I did the sync procedure and one of two tracks looks half green half gray which implies that they are 2 tracks in one. So to playback- do I listen that track only and mute the 2nd track? The issue is that if I listen that new 2 colors track only, it panned to one ear. If I unmute the 2nd track (the one it was set to align to), then it sounds left and right but I am not sure if this is how it supposed to be. I thought that after I sync, I should have 2 tracks in one and I would be able to put effects on that one track. Or would I still need to work with 2 tracks? Thank you.  

Thank you, Noel. I got some promising result. But should I pan the tracks left and right before I align (sync) them or keep them centered. And do I do it before I apply effects or after? Thank you.

swamptooth
I would disable fx on the track while you're using vocal sync, because it might obscure the results.

+1. And VocalSync wants to work with the raw vocal tracks because that way they'll at least be timbrally consistent.

Noel Borthwick [Cakewalk]
A clarification. Vocal sync and all region fx for that matter are applied at the clip level which are pre effects bin.
 
Either way you are free to add effects and panning as you wish since it has no effect on the vocalsync processing itself.

And another clarification to the clarification...the comment about effects is true if the processing is applied solely within SONAR, but some people record vocals through hardware processing they particularly like (e.g., the TC-Helicon or DigiTech processors). VocalSync doesn't seem to like those, so the solution is kind of like re-amping...monitor through the effect while you send the dry signal to SONAR. Then you can use the external insert on mixdown to get the sound you want.
 
Another problem can occur when someone sweetens up the voice with processing, bounces the clip to itself or applies DSP to make it permanent, and then decides prior to mixing to add VocalSync. Doubled and ADT voices are particularly hard to deal with. So I think it's always best to work with just raw vocals if you plan to use VocalSync, and apply any processing afterward.
 
The +1 was to Swamptooth's point about not using effects when working with VocalSync. If you have something like reverb happening, that will obscure the "real" decay so if you're trying to align the ends of phrases, the reverb can throw you off.
 
I guess the bottom line is I feel it's safest with VocalSync to a) record any vocals without processing, and b) apply VocalSync as early as possible in the recording process.

Not sure if you're addressing Noel or me, but here are my opinions. Of course they are totally subjective and are neither "right" nor "wrong."
 
First you have to decide on the intended impact of the vocals. I did a disturbing song about a returning veteran where everything was happening inside his head, so I wanted the vocals to be more diffuse. But with a pop song, you probably want strong, upfront vocals. With trance, the female vocals are often very diffuse so they'll blend in with the track more instead of stand out...they become more like another instrument. 
 
That said...I feel the strongest vocal will always be a good, solid, single voice. Doubling can dilute the impact among two vocals. However, you can augment the single voice to keep the strong qualities of the single voice with the more complete sound of doubling.
 
The VX-64's creates electronic doubling that is ideal for augmenting because you can place it in the background with the Presence control while the Stereo control adjusts the width. I prefer to widen it a little bit from the center so the voice is still centered, but bigger:
 

 
A little delay is also good but I don't like the delay to interfere with the voice. So, if you look at the Filter Mode and Cutoff controls, it's basically a high pass filter so there's no delay energy in the fundamental vocal frequencies. The delay rides "above" the vocals and gives more definition.
 
I did a shiny pop song that really shows off using stereo imaging, delay, and doubling to differentiate voices. Click here and then go to 2:20. There's a single voice, augmented exactly as described above. It doesn't sound like a doubled voice, just a "big" single voice. At 2:34, there's quadrupling of the vocals (not electronic, actual singing) and the four voices are panned to cover a much wider part of the stereo spectrum. These sound full, but not "big." At 2:38, the solo voice comes back and the contrast with the panned voices is very clear--even though it's only one voice, it's a lot stronger than the four voices.
 
Hope this helps.