The belt broke so I need to know where the timing marks should be in order to replace a broken cam gear and belt on 98 hyundai accent sohc

First you need to find out if this is a "safe" engine, a few are but most bend some valve when the belt goes (you could try turning gently by hand using the alternator belt) proceed as follows:-remove the drive belts, water pump pulleys, crank pulley, and the upper and lower timing covers.  You'll also need to remove the motor mount if 
You'll need to move the tensioner for installation of the new belt.  Loosen both the pivot and clamp bolts on the tensioner.  Pry the tensioner up and toward the back of the car, and when at the rearmost position, tighten the clamping bolt.

You'll also need to line up the camshaft and crankshaft to TDC.  There's a small hole in the camshaft sprocket that lines up with a notch in the front camshaft bearing cap.  The hole should be pretty much straight up when aligned.  There's a notch in the crankshaft sprocket that lines up with a *** on the front case of the engine.  If I recall correctly, this puts the Woodruff key at about 3:00 when aligned.  

Then install the timing belt with all the slack on the tensioner side.  Loosen the tensioner clamping bolt to release the tensioner, let it self-tension with the spring force, and retighten the clamping bolt.  Turn the engine clockwise with the crankshaft two crankshaft revolutions (1 cam revolution).  This will make sure you have the proper amount of slack on the tensioner side.  Recheck to make sure your marks are still aligned.  Then loosen the tensioner clamping bolt once again to let it self-adjust, and tighten the clamping and pivot bolts.  

After that, it's just a matter of putting everything back that you took off, but before doing anything, you may wish to consider that it's likely engine damage was done when the timing belt broke.  You may wish to pull the plugs and examine before you start anything mentioned above.  Evidence of anything hitting the plug is a sign of a valve broken off and probably a need for an entire engine.  You may also, after installing the timing belt, wish to bolt the crank pulley back on and see if the engine starts.  If the engine cranks quickly (lack of compression) and won't start, you've at least bent some valves and will need to remove the cylinder head.