I have a Lenovo G505 laptop. I need to take some pictures. How do I transfer the pictures to a file?

Depends on what camera you use. Is this the built-in one?
Then run some software that uses a camera to capture images. Skype is an example. Others are graphics programs that look for a TWAIN device.
There you will see options to save images to files in different formats.
If you mean an external camera, you might read its user guide or manual. A USB cable might link with that Lenovo. Or a data card like an SD or similar might work.