Loss of colour when copying and pasting image

Hey guys, I'm new here. Pleasssse help me.

When I use the polyagonal lassoo (or whatever it's called), select copy, then paste the selected image onto a new blank file, the selection changes from colour to black and white- which is very frustrating. How do I fix this problem?

Sounds like the Colour Mode of the new blank document is set to grayscale. If it is, then any colour paste will be converted.

Try creating a new blank document and see what the colour mode is set to.