I'm guessing you could mean an Asus2/C#. In the open
position, this is fairly simple to pull off.
Start with the Asus2.
Basically, the sus2 chord
involves replacing the 3rd of the major chord with the 2nd
note of its scale. Note that this is a good movable chord.
Then on to the Asus2/C#
You'll notice the chord just
adds the C# in the bass.
I recall this chord in the riff to Metallica's "Hero of the Day".
I would typically play the E, and A with the first finger, and
the C# with the third, or whichever is comfortable for you.