Hi there,

I'd like to create a 2 or 3 column menu, cause i have a lot of items under it. How can i do that?

You could try to put at your custom.css file these:

.mainHeader ul.menu ul {width:500px;}
.mainHeader ul.menu ul > li {width:50%;display:inline-block;}
.mainHeader ul.menu ul li > ul {left:500px;width:250px;}
.mainHeader ul.menu ul li > ul li {display:block;width:auto;}

These are for a 2-column submenus. If you need for 3-column you can change the li's width.
It might need some more customizing for the tablet and mobile views but let's start one step at a time.