rust ahoy

[fico]

so yeah i bought my car 32 days ago and the person i bought it from is very clever...he also happes to bemy family mechanic ( not mine i preffer to do my own repairs) but he painted the frame the same color as the underside of thecar so when i looked for rust i didnt see any....then last weekend when i swapped in my SR20 i looked closer when the engine was not in the compartment and i saw all the rust (ill get pix up asap) but the frame in the front is rusted through one 1/2 on the drivers side about 7 inches long, so what is there to do about this? i know its hard to give advice with out pictures but just some general things like do i replace that part of frame? or what ill get pix up when i find my camera