I am trying to create wireframes for Win 8 and i am using Blend so as to make wireframes as close to actual app as possible.
IS there any short quickstart guide which i can read to start designing the UI in Blend?
I did google online but most of them very vague in description on how to design UI.
Normally you would use something as sketchflow to create your wireframes, but that's not available for Windows Store. Only for WPF, Silverlight and Windows Phone (phone req. download from codeplex).
To create wireframes you would need to use something else like Microsoft Powerpoint. Please note though, to do this you one of the following versions of Visual Studio to create wireframes in Powerpoint:
If you want to use PowerPoint for wireframing; check this Microsoft guide out
Hint: if using Powerpoint: If you search the Visual Studio Gallery for “storyboard”, you’ll find that the lots of shapes there. The link to the gallery and search is here.
You can still use Blend to create some mock ups. You just need to drag the controls onto the screen and start laying out your app. However this isn't wireframing, this is actually building a prototype of the app rather than doing your wireframes, which is a different thing. You can still create your content in only using Blend and the Properties Panel on the right side of the screen.
There's a ton to material available here on the general design portal for Windows Store apps: http://design.windows.com
If you want wireframes looking as close as possible to the real deal, without actually building it, I recommend doing the wireframes in either Adobe Illustrator or Adobe Photoshop. There a lot of assets available for designing screens here