Sign in too instagram on the computer instead of the phone?

You can access Instagram from any web browser on your computer, such as Safari or Google Chrome. Go to www.instagram.com. Type instagram.com in your address bar and hit the Enter button. Click on the "Log in" link.

BTW, if you want to know how to upload 4K to?instagram, here is the guide.

Http://instagram.com/ then click the [login] button on the right side and log in with your user name and password.
you can only add new people to follow with your phone though the access on the PC is extremely limited