can I use my roku with my computer?
If you mean can you connect the Roku to your computer and see it on the display, the answer is no. Computers do not have HDMI video inputs (unless they've been specifically built for video processing). So there's no way to see the Roku screen on your laptop display. A desktop display might have an HDMI input, same as a TV set, which would allow the Roku to be seen, but it would have nothing to do with the computer and you wouldn't be able to use the computer while the Roku is using the display.
If you mean can you display your computer screen on the Roku, the answer is maybe. A Windows 10 laptop should be able to screen mirror to the Roku using the Project function of Windows. Android devices (tablets and phones) can screen share, but iOS devices cannot.