How to decorate my house using both modern and classic combination?

It can be done, but you have be careful not to end up with a Hodge-podge look. If you are looking to use contemporary furniture, then use the antiques sparingly but with huge impact. For instance, a neutral or white sofa with a couple of similar side chairs could be beautifully set off by a dark wood antique sofa table or a dark antique sideboard directly against a light colored wall with maybe a single large ornamental piece set off to one side with no other accessories. I’d be leery of using too many antiques in one space or of using too many “classic” accessories. i.e. lamps. rugs. pillows.
Regardless of your choices, keep you color palette between both styles the same and minimize the use of the true “classics”. This will also give more weight to the true antiques in the room if they are using sparingly.

Have fun!