You don't, really. The closest you can get is to 'boost' a post, which you can do by clicking on the square beneath the post that is just to the left of the star for 'favoriting' them.
@XaoslordErie I see. I wonder if it’s a feature they’d ever considering adding, as I have to admit, it’s a bit tedious to scroll through all of my notifications to find replies I haven’t yet answered if I’ve been busy for a while. 🥺 Having this feature really helps me out on Twitter, Mastodon and Spoutible when it comes to be replying/catching up with people’s replies, so it’s a bit of a blow I can’t do it here too. 😢💖💙 Xxxx
@XaoslordErie Thanks, I’ll send him a message on here and see if he gets back to me. Will let you know. 🙂💙💖 Xxxx
@XaoslordErie Ah I didn’t realise that, thanks for telling me. Are there any other notable exclusive features/benefits to being a Pro subscriber? If yes, I’d love to know that for if I consider doing so. I did send a message out in the open to the person you mentioned to me about some of the issues/queries I had and they did reply. As promised, I said I’d let you know what they said, so here you go. 🙂😘💖💙 Xxxx
@rosielebontennant
Bear in mind that you cannot DM another user unless you are a Pro subscriber, though you can respond to a DM if someone else sends you one. You just can't initiate them on your own. Likely your best bet is to reply to one of his posts, and ask about it that way.