How to construct (draw) a 30 degree angle with compass and straightedge or ruler - Math Open Reference
Or construct a equilateral triangle using the wiki link and figure out how to divide an angle in two...
These take a bit of time to explain so google is the best bet.
Actually, if you want to find 30 degree angle with compass and ruler, you can do like this:
A. Draw an equilateral triangle:
Step 1: Draw a random line.
Step 2: Put the point of your compass at one end of the segment and the pencil point at the other.
Step 3: Without moving the point of the compass and without changing how wide it is set, swing the compass in approximately a quarter-circle (up & away from the line segment).
Step 4: Without changing how wide the compass is spread, move the compass point to the other end.
Step 5: Swing the compass so that the arc you are creating crosses the arc you drew in step 3.
Step 6: Mark the place where the two arcs cross.
Step 7: Using a ruler, draw line segments that connect the spot where the arcs cross to each end of the original line segment.
B. Draw a height of the triangle.