Re: Black spot in the center of the image viewed in...
If this is a Newtonian reflector or a catadioptric scope (Schmidt Cassegrain or Maksutov) you may be trying to use it at too low of a magnification. Your magnification needs to be high enough that the exit pupil is less than 5 mm; to figure this divide the focal length of the eyepiece by the f-ratio of the optical tube. If this quotient is 5 mm or more the black spot you are seeing is the shadow of the secondary mirror.
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First find a local Astronomy club -- the members will help you.
Second, you must first align the red dot finder with the main tube-- there are knobs on the side and bottom (usually) to move the red dot. Point the scope at the top of a telephone pole in the distance during the day time-- wget the top in the center of the eyepiece of the main tube. Without moving the main tube adjust the red dot so it points at the exact same spot.
Turning it all the way in or out is NOT how you focus-- there is a small "spot" when the eyepiece is in focus, and every other eyepiece must be refocused. Turn the knob slowly until the star or the moon comes to sharp focus.
Stars will always appear as points. It is not possible to magnify them enough to see them as disks because they are all extremely far away. A telescope will however show you stars and other objects that are too dim to see with the naked eye.
You will be able to see the planets as disks, and even features on the planets, such as the bands on Jupiter, the rings of Saturn and the phases of Venus, and also moons around some planets. There are other objects that will show more detail when magnified, such as nebula. You will be able to see a lot of craters and other detail on the Moon.
Your problem is simply that you are not pointing the telescope at these objects. This seems to be one of those telescopes that "automatically" finds objects, but these so called "go to" scopes only do this when they are set up properly. I can't say what step(s) you have missed, but clearly even if the scope thinks it is pointed at the moon, if you can't see the moon, it is NOT pointed there. The Moon will fill the field of view even with the least powerful eyepiece. If you are seeing stars as points, then the eyepiece is focussed and working properly.
Eyepieces are for the most part interchangeable. Your scope will have a focuser on it in one of 3 diameters. 2", 1.25", and the rare .965". Most inexpensive scope will use a 1.25" eyepiece. 2" focusers are usually found on more expensive scopes used for astrophotography due to the increased field of view with the larger diameter. Plossl eyepieces are fairly inexpensive and are good for all around use. I would suggest getting 2 one at 25mm or greater and one around 9mm. http://www.telescopes.com has a large selection however their are many suppliers out there. Good luck and happy star hopping
Ensure focusing is spot on. if your image is a black dot surrounded by white light (like a doughnut) then your not in focus. Look at making a Hartmann Mask (really easy, just google for it), which fits over the front lens. It has 2 or more holes in it,this means when you look through the eye piece you will see double images, adjust focus until the images merge into one (if the images go further apart turn the focuser the other way), when they are merged remove the mask and presto you should be in optimum focus. Always remember telescopes are very sensitive and focussing requires delicate adjustments.
Regards and Clear Skies
The problem is you are way out of focus. Turn the focus knob alot, until the star image gets much much smaller. Keep going until it looks like a pin point or a star!. The spider vane and center black dot will disappear. This black dot is actually the secondary diagonal mirror reflection in the primary mirror. The peace signs are the secondary supports. Use the lowest power eye pieces. I would not use the Barlow lens that comes with this scope as it very poor quality. Also, using this high power with this small an aperature (tube diamter) & unstable mount will be very difficult indeed. Invest in some wide angle, long eye relief low power lens. Use these for a while before going to higher powers.