Upload a JPG — it's hashed locally and reduced to a tiny grayscale thumbnail (a real .jpg's own header overhead is too big for one memo). Clicking Send broadcasts one real Solana transaction (a 0.000005 SOL transfer + a memo carrying that thumbnail) to the destination wallet. Got sent one? Redeem it below with the transaction link.
Paste the Solscan / Explorer link (or the bare signature) of the transaction you received — the image comes straight out of its memo.