How do I ask her this without making her seem like she's dumb?

I don't think this girl I was talking to, full understands insta. I not only had to explain to her the other day, that you have to be following someone (usually), now, in order to DM though (so, a mutual follow), but, now that she is (since I explained that to her), but, now, she's for some reason not reading my messages. Before you say "well she's not in to you", trust me, that' not the case, I know for a fact she is, so, please don't say that. But, so, if she is, and I had to explain to her that in order to DM people you have to have a mutual following between the two, that she's now not reading my messages.

My feeling is that, she doesn't actually know where DM's are, that she's only ignoring them because she doesn't know how to DM or where to go on insta.

I unfortunately failed to get her phone number, so, i can't text her, which of course, would have been easier at this point, in messaging her but, to be fair, i never asked her for it, and never gave her mine, because I wasn't thinking about it at the time.

So, I may just go see her, and make sure she knows how to check DM's and all that, I just don't want to make her feel like she's dumb, because of it, so how do I go about that

How do I ask her this without making her seem like she's dumb?
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