You mean these?


Those are called drop bars. You could add them,but you'll need to change out many parts,and it can get expensive.

You might want to try a set of trekking bars:


They'll bolt straight on,and you can use all your stock components. If you search around the site,you'll find several threads about them.

Also +1 Retro Grouch's comment about swapping your knobbies for some street tires. That will make a big difference.