Tycho Sky is an overlay of the Tycho-2 star catalog and the DAML02 cluster catalog on a background image taken from several infrared surveys (Glimpse/MIPSGAL, GLIMPSE360 and WISE).
Tycho Sky is one component of the Tycho Explorer, which also includes Tycho Galaxy, a face-on map of the solar neighbourhood as seen from above the galactic plane that is derived from the Tycho-Gaia Astrometric Solution.
The background image has a number of artifacts that I will describe at some point on my blog.
The star colours are derived from the B - V colour index computed from data in the Tycho-2 catalog and the size is derived from the star's relative magnitude. (You will not see the stars until you zoom into the image.)
You can pan and zoom to any object with coordinates in the SIMBAD astronomy database by entering an identifier in the search box at the upper right. Beneath the search box are four options:
At the upper left are controls to zoom in and out, return to the home view, and expand to full screen mode.
You can also move left, right, up and down by dragging your mouse, using the arrow keys, or using the WASD keys. You can zoom in and out using the + and - keys or your mouse wheel.
Clicking or tapping will zoom into the current position. Double clicking/tapping will move the reticle to the current location of the tap or mouse pointer.
At high zoom levels, hovering your mouse pointer over a star or cluster boundary will show the name of the object and a distance estimate if available. Tapping or clicking will bring up a popup table with more information (and a link to Tycho Galaxy for stars with distances).
The galactic longitude and latitude of the current mouse pointer location appear at the lower left.