"I use Facebook every day."
"I use Twitter every day."
Obviously, "use" is correct here.
Two things I'd like to add:
< No longer needed. >
2. I suppose you meant: I use Facebook 'every day', instead of 'everyday'.
Each day = Every day
Example: "I go to the beach every day."
Ordinary = Everyday
Example: Ordinary English = Everyday English
Since the abbreviation SNS would seem not to be in common use (or else Myridon wouldn't have asked, and I'd never come across it either before now), the question of what it stands for is a bit pointless. But yes, one hears the term"social networking" widely, probably more often followed by the word "sites" than "services", and those three-word terms are often contracted to the two-word "social networks".
To return to the original question, the answer given in #4 (use "use") is certainly correct, but I wouldn't entirely rule out "do". The verb "do", especially in informal contexts, does service in more roles than you're likely to find in most dictionaries:
A: "OK, I look forward to seeing you at the meeting. Once I've decided exactly when and where it's going to be, I'll email you the details. What's your address?"
B: "Sorry, I don't do email. But you can text me on 07123 456789."
When somebody phones me up about something, and I want them to put their request in writing, I might ask them "Do you do email at all? That would be the easiest way to write to me."
But I suspect that this use of "do" is more common in the negative or interrogative than the positive.
Only two phrases I posted on this threat has posed a couple of controvertial points.
At the same time, I realized that everyday cannot be used as adverbe and the word "SNS" is not that common as in Japan.