Hi, I'm using Tascam us 2x2 audio interface on Sonar LE.
I pluged in my guitar to one of my inputs on my sound card,
and Iwant to record my guitar on STEREO track and not on MONO track As it is now.
How am I do it?
How do I play an audio track has stereo track after I recorded it has mono track?
Thanks!

That's easy. Just record it twice and than pan tracks as you wish.

Sorry, but I don't quite understand what you told me to do.
I am new to this software :(

Hi. You can right click on the clip, and choose convert to stereo. 
All the best.

You need two mics to record stereo. They can be place a few feet apart or you can have one close micing and the other some distance away. Adjust the input level on the audio interface so they have a similar level.
 
Most think, and I am one too, that an instrument that is mono, which is most, should be recorded as mono. Pianos and drums can be thought of as stereo.  

Zargg71
Hi. You can right click on the clip, and choose convert to stereo. 
All the best.

This^^^  A guitar or mic is inherently mono, so you need to convert it to stereo. However, if you insert a plug-in that's stereo, most will generate a stereo output from a mono input so that's another way to get stereo. 

I'm repeating a bit of what's already above, but there are a couple ways to achieve this, depending on what you're looking for. 
 
Since your originating instrument (guitar) is mono, just converting the track to stereo may or may not give you the desired result you're looking for. 
 
Another option is to record it once (in mono), clone the track you just recorded and pan the two resulting tracks left and right.  Bear in mind, this won't sound any "fatter", as it's the exact same signal, just taking up a wider portion of the stereo spectrum, and it will sound louder, since you're adding more of the same signal. 
 
If you want a 'fatter' sound, take the advice that Soundwise gave above - record your guitar two separate times on two different tracks, then pan those tracks left and right as wide as you want.  Not only will this give you the wider / stereo sounding guitars, but it will sound much fatter than just cloning a single mono track and panning it similarly.
 
Hope this helps.
Russ
 

karma1959
 
 
Another option is to record it once (in mono), clone the track you just recorded and pan the two resulting tracks left and right.  Bear in mind, this won't sound any "fatter", as it's the exact same signal, just taking up a wider portion of the stereo spectrum, and it will sound louder, since you're adding more of the same signal. 
 

This. After you create two tracks, you can fiddle with the equalization to achieve a broader sound.

If you record a mono track, like a guitar, it will play back as stereo track.  There is no need to record a mono instrument in stereo if you just want it to play back in both speakers. 

a stereo track where one side is a 100% clone has no advantages.
Use mono for mono instruments and mics, and then pan left-to-right.