My preference will be to tell him some stories, words, poems and writing alphabets and small words rather than going for smartphones and computers.
'Idhuvum Kadandhu Pogum "
Even this challenging situation would ease
Many research has shown that exposure to radiations from smartphones and the likes affect the tender ones since their brain is at developmental stage, so it is recommended not to allow a child to play with these smart devices for a long time. I never tried to hurt the author of this thread in any way, I just want the children to flourish in their own way. Let them sing, dance and play a little more by keeping them out of these complicated gadgets.
"Life is easier when you enjoy what you do"
I do not think the query is about getting a 5-year-old to actually start blogging or check out ISC. The discussion to be elicited is the manner in which to make the child understand what blogging is about, what working at ISC is about. The query seems to be raised, perhaps, because the child has asked out of general curiosity what the thread author is doing while on a computer.
Kids are always keen to know what the adults are doing when they themselves are bored and not having anything interesting to do. They will come up to the table and get inquisitive as to what is going on, what is this work that the parent/relation is constantly doing on the computer? It could be explained in a way that the kid understands. Perhaps you could say that, like writing on paper, you are writing on a page on the screen, that, like a book or a diary, you have created one which is called a blog where you put your ideas, thoughts and general information. You can explain ISC as a place where information is given by people who join as members, just as many people write for a magazine. You can talk about the forum as a place where people talk about things, just like how people have conversations in actual life. The child's curiosity should be vetted in a way that you can convey the information in a sensible way with simple words and easy language. The child may pick up vocabulary, too, this way, such as "blog" or "website".
I see no harm in exposing a kid to such information. If you avoid, then likely the child will think it is something wrong or not to be known by a small child and the child may even get some incorrect impression. What is wrong in explaining to a child about the legitimate work you do?
When people come at you with their worst, you should come at them with your best (advice given to Selena Gomez by her mother, quoted in Time magazine.)