Not sure I can fully resolve this for you remotely, but here are a few thoughts. First, to install the upgraded driver you just need to download the software from the Epson web site (which I presume that you have already done) and then double-click the installer to run it. From here the installation process is pretty automatic.

If you are printing from Photoshop, the broad outlines are that you first need to go to Printer Setup and select your printer and the right paper size and orientation. Then choose Print. Have Photoshop manage colors, and make other appropriate settings in this box. Then click the print button to see the second print dialog. Here you may have to again select your printer and choose your paper and some other parameters. In this dialog be sure to select the option that does NOT have the Epson printer software manage colors – turn printer color management off.

Dan