New tires for a newbie's bike
 

Hello everyone! Just a simple question... I bought new tires "Vittoria Diamante Pro 700X23c" for my bike and there's no indication on the rotation direction I must mount the tires if I compare with the tires actually on my bike which have an arrow indicating the rotation direction. How can I know which side I must mount my new tires?

Thanks to all in advance for your future answers!

you might try posting this in the road cycling forum - but to me that tire looks totally slick and I can't imagine it would matter what direction it should roll

Yeah, what he said. Tread barely matters on road tires, if it matters at all--if it were important, we wouldn't still be having debates about slick vs. tread and all that other stuff. The contact patch (part that touches the ground) is so small relative to the weight of bike and rider that the rubber just cuts through whatever's on the pavement. you can make up scenarios where a little tread might help or where a slick would increase the contact area, but in real riding it's rare.
Having said that, it's traditional (for no practical reason) to mount tires so the label can be read from the right side of the bike, the drive side. Same with hubs and rims: Everything goes so it can be read from the right side or from the saddle, whichever applies. but there's no reason it has to be that way.