Create two VLANs, 100 & 150.
Check your PCs on the network - you need to find out what the Default Gateway is for PCs on each subnet.
Configure the default gateway IP address for 192.168.78.0/24 network as the IP address on the VLAN100 interface.
Configure the default gateway IP address for 192.168.76.0/24 network as the IP address on the VLAN150 interface.
Find the switchport that your "Red" network is patched to, and configure that switchport to be an Access port on VLAN 100.
Find the switchport that your "Blue/Black" network is patched to, and configure that switchport to be an Access port on VLAN 150.