Hiya, my question is. Can i download any textures and projects to Unity 3 ? or can you draw the projects on your own in other program and paste it into unity because i want to make a gun but i can't do it in unity because i cant draw a straight lines in there... Please help me, And sorry for my english.
Yes, one of the strengths of Unity is that you can use assets(textures, models, sounds, objects, scripts) from many programs and add them to Unity: http://unity3d.com/unity/editor/importing
By projects I assume you mean 3d models? Yes Unity supports most image formats for textures. You can easily add them to your project.
For getting guns/objects into your scene create a 3d model in a 3d model program such as Blender/3d max or Maya and import it. You can also set your textures within the 3d modelling program.