I have a little
problem with css, k2 I installed 2.3 and when I added the writing
addthis.com have moved to the right than not entering into their space. How can I fix it? I'm not good with css.

Please send a link to your page if its not on localhost

www.supercreative.it/Realizzazioni/Decoupage/Vaso-con-le-conchiglie.html
this is just an example

Use firebug to turn text-align: right on and off to see if this is what you want. The code is in k2.css around line 152
Please remember that this will affect all your items. If you want different results for different categories read about using k2 template overrides

Thanks I solved