Install a Lan card

Solution
Sure you can - the board has two PCI Express slots, one of which is a x16 and the other a x1:

http://www.biostar.com.tw/app/en/mb/introduction.php?S_ID=685#specification

What you are referring to is more commonly called a network card - same thing though.

If you buy a PCI Express x16 network card (recommended), you must install it in the x16 slot of your motherboard as it won't fit in the other slot.

Of course, I'm assuming the x16 slot isn't already occupied.
Sure you can - the board has two PCI Express slots, one of which is a x16 and the other a x1:

http://www.biostar.com.tw/app/en/mb/introduction.php?S_ID=685#specification

What you are referring to is more commonly called a network card - same thing though.

If you buy a PCI Express x16 network card (recommended), you must install it in the x16 slot of your motherboard as it won't fit in the other slot.

Of course, I'm assuming the x16 slot isn't already occupied.
 
Solution
Those are server class products with multiple ports. Expensive ones. For a desktop - absolutely unnecessary.

Regular PCIE x1 network adapter is perfectly fine.