Make sure you use a heavy duty extension cord to plug your chipper into the electricity. Then make sure the interlock safety switch on the bin is in the up position.
Take a look at the top of the chipper and you will see the enlarged side of the feeder slot.
Here it has a small twig sticking out of it. This is the spot you want to aim your material into to get the best connection and chewing action from the blades.
The little twig you see here is probably not going to get too chipped up unless I put some more twigs with it to make a more solid connection with the blades instead of just wrapping around them. Sometimes holding on to smaller stems is helpful also as long as you don't put your hand into the feeder. You should also wear eye protection when working near the feeder.
Here you see a bundle of twigs put into the feeder at the same time to facilitate better chipping action from the blades.
Once you have done a bit of chipping and you notice the chipping action is not working well, look to see if the already chipped material is piled up in the front of the bin and not allowing more material to fall through the exit chamber. Wiggle the chipper a bit to make the bin contents flatten out. It might also be helpful to work on a slight incline so gravity will help the chipped material fall backwards into the back of the bin.
This is the inside of my compost tumbler with shredded material mixed into it. It looks much better than the twigs in the chipper in the previous photo.
Very small items like straw and leaves do not need to be shredded, and sometimes the tiniest stems will pass through the chipper intact. They will usually decompose with the rest of the material. You can always sift them out of the finished compost if they do not, or if only partially decomposed, they can go back into the composter for another session to finish them off.

When the bin is full or you are finished chipping, you will need to lower the interlocking bin handle before you can pull the bin out of the stand and empty it. You will pull it out from the end on the opposite side of the handle.
Then you can unplug your chipper/shredder from the extension cord, cover it and store it until you have another bundle of twigs and stems to chip up.
TIP:You can use your chipped up twigs and stems as a mulch for your flower bed instead of putting them into the composter, although if composted they will feed your beds about two to three years faster.