Open a web browser and navigate to the Instagram website. Log in to your account. Click on the profile icon in the right-hand corner to go to your profile page. On your profile page, click on the "+" symbol in the centre of the page. Click on the "Upload" button and select a photo or video regarding how to post on instagram from pc. Enter a caption for your post and include any hashtags you wish to use. Then click on the "Share" button to post it to your Instagram feed.