The parallax angle is given in units of arcseconds. The distance to the star is given by the formula
d = 1/p,
where d is the distance to the star in parsecs (1 pc = 3.26 light-years) and p is the parallax angle in arc seconds.
Let's practice. You can access a tool that shows an image of the sky with all Hipparcos data here (it will open in a new window). Read the directions on the page, then start the Java applet. Enter the coordinates given for Sirius and click on View. The applet will draw the region of sky around Sirius. The blue points are in the Hipparcos catalog and the Tycho catalog (objects in the Hipparcos catalog were measured with greater precision) and the white points are only in the Tycho catalog. The larger the circle, the brighter the star. Click on Sirius, the largest star in the middle, then click Get Info. Another window will open with a lot of information. You are most interested in line H11, Trigonometric parallax.
For Sirius, the parallax is 379.21 milliarcseconds. Plugging into our formula gives a distance of 2.637 parsecs. Converting to light-years gives a distance of 8.6 light-years.