Cannot see an image through the lens
I bought one of these telescopes, and had trouble at first, but finally got some decent results. If you dont have any experience with telescopes, I suggest trying it first in daytime, since daytime objects are much better for getting experience. Also, start with the lowest power eyepiece, the 12mm 50x, the one with the largest lens. Start by looking towards something pretty big, like a car or a house, and it needs to be some distance away to even have a chance to get a focus. If your target is closer than about 1/4 mile, you should add the right angle eyepiece attachment to allow you to focus in on closer objects.
When you are finally set up with the low power eyepiece, and have a good big target in the daytime, start looking thru the telescope while turning the knob thru the entire range. At some point of knob turning, you should see some image appear in the eyepiece..Turn the knob slowly to focus it clearly.
And this is for the shaky tripod. If you can hang a book under the middle of the tripod, the added weight will help stabilize the telescope, and you should be able to see a little better, without so much motion at the slightest touch.
After you look at the first car or house, you can start to see how careful you have to be to use the telescope, and you can start to look at other objects. When you move to the higher power 100x eyepiece, it will be even more critical in getting it both aimed and focused. If its off by just a few degrees, you wont see what you are looking for.
When you start nightime viewing, start with the largest object in the sky, the moon. Its the same process as daytime, except the eyepiece mechanism will have to be adjusted a little closer to the main body of the telescope.
Viewing planets and stars will be the ultimate test. Stars and planets are harder to see, since they are small, and hard to see unless they are in focus. When you can see those views, you have passed the telescope test. Its a matter of careful aim, and having the telescope focus set close to the point where you can see objects that are VERY FAR AWAY. If you are able to focus on the moon, you will be fairly close to being able to focus on the planets. The hardest part is actually getting the planet in the view of the telescope, in other words, aiming it.
The last item that can really mess up the view is a fogged up lens. Usually this happens in the summer when the scope has been in the air-conditioned room, and then it fogs up when taken outside. The solution for this is to let the telescope sit outside for 20 minutes, so the fogged lenses can clear. By the way, the same fogging may happen when you bring the telescope inside during the winter.
I hope this helps you eventually get a clear view of some amazing views in the sky. Your final exam is to take a look at the moon, the rings of Saturn, and the moons of Jupiter, some time in the near future. Have Fun!