can i get any videos to help me design a telescope?
Not that I am aware of... Try to find measurements of a telescope. If you can't, then just design your own. To make lenses, you'd probably need to make two arcs (one and then another a about 1/8 of an inch or so away) and then connect them with a line and extrude. Go to the top view and create a sketch of a circle. Make it the diameter you want the lens to be. Extrude the circle so that it cuts into the arc extrusion from earlier. This should give you a lens. If this does not work, let me know through the GrabCad email system. If it does work, send me the file and I'll see what I can do to help even more or find flaws for you.
Try this video.. and dont worry if you dont know solidworks.. it is very easy to learn.... if you want to design in autodesk inventor then no worries follow the same steps in inventor... every CAD software has the same options. only the interface and the name changes...