Sure ildperez!

First things first.  By default a new tab comes as a multiple of 5 in one, so we need to break your new tab down to a single.  

From the tab's settings under Tabs and Styles let's remove tabs 5, 4, 3, and 2. 

So now you have a single tab cleverly named Tab 1 and you want to reshape it so it can slide up or down, left or right length wise. 

All you need to do is pull the tab away from the wall, grab the tab's corner, get your cursor's resizer going and resize it, from short to long, then from wide to slim.

Take your time, it's really easy to reshape tabs.

Once you're happy attach the tab where you want it, it will slide in and out from there.  You may have to right click then click attach to edge first.  If it's stubborn after that, just click away anywhere on your screen and it should attach.

Lastly, you may want to change your brand new single tab's name from Tab 1!

Click here for shot with open tab

Excellent!

Remember this.  The more icons you add and if a single row tab isn't long enough, you'll see the icons with this +.

The plus sign means next single row of icons in this tab.

If you don't want to see this, simply reshape the tab first wider then longer until all of your icons fit into a single row.

Once you get the tab long enough for all of your icons to fit into one row, resize the tab's width back to slim again then reattach.