how can i open a stl file?

i have a question: how can i open a .stl file? i use sketchup from google can i open with this? also autocad but i don´t know how i can open the file. please someone help me i will be so grateful

You should be able to import it into autocad. If not you can import it into Blender, Meshlab, or Netfabb. All free programs.

Here's a free Sketchup STL import plugin.

thank you now it works perfectly fine