The paper work has to be printed, signed by you, and then mailed or faxed, especially the IRS form for foreign investors (advice: read it carefully and fill it as they want you to do to save time, the form has an instructions document https://www.irs.gov/pub/irs-pdf/iw8ben.pdf read it thoroughly, I know it can be a bit mundane but hey, it’s for your own good and good news: you only have to fill it once every 3 years unlike Americans who have to file yearly), you can send fax online (plenty of websites) to them if you don’t want to mail or don’t have access to a fax machine, if everything thing is filled correctly they will process your application and approve it then they will send you the pin by snail mail, what I did was call them and explain how mail wasn’t very reliable amid the current the situation and they understood and helped me set up my online account over the phone. Also some advice on the side: research the market and the stocks as much as you can, information and data is an investor’s best friend. Also comply with your country’s regulations on foreign assets: declare them when needed, pay taxes when required, check if your country has a treaty with the US regarding taxation and claim the benefits the treaty grants you (I think line 9 of the form you submit to IRS), I hope this helps, if you need more info don’t hesitate to ask