Whom to teach
You definitely can teach beginners. Showing scoring, atari, ladders, simple shapes and tsumego is not a problem at all, and as your students improve, you will still be able to give them a few hints, show them tesuji and shapes they missed.
You should however bear in mind that your knowledge is limited. You can't be completely sure about some things, so it is a good idea to tell when you're not sure, and to give ideas and reasons instead of just telling "this is wrong, and this is right".
Another good idea is to keep a reasonable distance between you and your students. Personally, I prefer to teach people around 4 to 9 stones weaker. If they are closer, it's a little hard to teach, instead it becomes more of a joined study session (which is not necessarily bad, but it's simply not "teaching"). If they are further apart, I tend to dive into details too quickly and confuse them with too advanced thoughts, but this is probably just my personal weakness.
There is one aspect to this that greatly helped me when I was DDK. At that time I had several teachers that were advancing the ranks at a similar pace as I did, and they were just a little step faster. This meant that they clearly remember the mistakes they just fixed in their play. A teacher who is many stones stronger won't necessarily remember which tesuji is learned at what level, while those slightly in front of you more often do.
It may be useful to copy from the lessons of stronger teachers or from books. Those resources tend to be reliable, and give you a good overview of what to cover in a certain topic. For instance, if you recently read a book about various 3-3 joseki variants, or about a specific fighting shape, or a cool yose tesuji, then transfer your newly acquired knowledge to your student: Ask him if he's interested in learning about an awesome tesuji, and show him!
Like this, you will certainly get some questions that you didn't think of yourself yet. If you're reasonably sure about the answer, tell him, else, refer to your original teacher (or the book) to inquire about it. The nice side effect is that you gain a more thorough understanding yourself.