Internet access across multiple VLAN's

Hi all,

First of all I apologize if this kind of post is prohibited here however I believe that this may be the best place to find a solution to a problem I have.

Network topology

I have an existing internet gateway through which I need to allow multiple vlans to gain access. The gateway is connected to a managed switch which has the interfaces for all my vlans. The gateway providing the internet also has a DHCP service enabled. So I guess what im asking is how my vlan on subnet 10.255.100.0 would gain internet access through the gateway 192.168.100.99? In the end I'd like all vlans on my side to gain internet access.