The servo block needs to be assembled before you can use it - finf the parts in the picture from your kit. You can click on the picture to zoom in.
Using the 2 bolts and nuts, fix the servo into the board like the picture.
Push the 4 spacers into the holes - be careful, the ends are different! The end with the step should be pushed into the board - you will have to look closely.
You can also use the brackets and bolts to mount the servo horizontally if you want.
Finally, you need the small screw from the other bag of parts - keep the rest of them, you might want them for advanced projects later!
Push on the large servo arm, and hold it in place with the small screw and washer. That's it - you can now attach other things to the arm with the larger bolts and construction kit parts.