Yes, usually I do ask. Even though I know it's not necessary to ask for permission, I still think it's polite and friendly to contact them. But in these cases, I can't be sure that they could understand an English message. If their sites offered English translations, I would give it a try.
Actually, the desainew one seems familiar - I think he does speak at least a little English, and has posted in a forum or on the website (can't remember which). Might try messaging that one.
I found a 4th site too. But the comments below the tutorials (in a blog format) aren't being moderated (too many viagra ads) so I won't use that one.
Anyway, thanks for having a look, Moini!