Now, I want to buy/donate using BTC

I want to donate to my favorite social media site and all I have is Monero (XMR). I think I get that you have to buy BTC with XMR for any online purchases and it looks like my wallet has a way to send BTC. How do I copy all those address and destination digits on the page in my wallet if I only have a phone?

You can use our ChangeNow integration to send your XMR and have the other end receive BTC. Check this out: FAQ — LocalMonero.