I have been asked to design a network topology as per the given requirements in my assignment. I've already created the network topology using visio, but I am not sure if its correct. So I need someone to have a look at it.
Not in the manner you're asking.
Lets say you have an assignment involving visio, and you can't quite beat the thing into submission, sure. Ask a specific question of the sort you see here.
If you want someone to vet your homework, or to do your homework, no.
No. This site is to help people having problems and seeking answers about their PC. If you need help on your homework then you should look for a site more catered to your needs.
On the other hand, if they are questions based on programs (for instance powerpoint) then I'm sure you can ask them here.