Companies often post requirements for virtual interns on job and internship portals, websites, and their social media pages. You can either look for roles on the portals or run a search on Google to find online internship options.
Alternatively, prepare a list of companies you admire and would like to work with. Follow them on LinkedIn and other social media channels and keep an eye out for intern openings. Visit their website and check for open positions.
You can also email them expressing your intent to work with them. If your acquaintances are interning somewhere, you can also request them to recommend you.
Every organization will have a dedicated registration page where you can fill in your details and upload your resume and required documents. Some employers may also ask you to email the documents.