Can I convert a DVI port to a VGA port to connect my VGA monitor?

Depending on the type of DVI port you may or may not be able to, DVI-D ports don’t support being converted to VGA, however DVI-I does.

You can easily identify which your graphics card has by looking at the flat bladed pin which is at one end of the DVI port, if it has 4 pins surrounding it (one in each corner if you will) then it is a DVI-I port which can be used for a VGA signal.