The big yellow circle is the corner light. To have the sidemarker flash WITH the corner light, follow the diagram.
To wire the sidemarker so that it is CONTINUOUSLY ON and flashes OUT of sync when your turn signals are on, just wire the negative (sidemarker) wire to the red (corner light) wire.
For the full installation guide, visit TEAM DEL SOL It's got really good instructions and pictures on how to cut the fender and install the lights.