9th grade biology help. How do you read DNA sequence?

It is when researchers add dye to read the DNA sequence. IF DNA polymerase is using the strand of DNA to synthesize and make a new strand and scientists add dye to some of the bases how exactly do they read the ENTIRE sequence. Since the synthesis is stopped everytime a dye colored base is added then there will be several strands of DNA. Researchers can then yze the bases and look at the dye. But still the dye only has information for some specific bases. So how the hell do they use the dye to map out the entire dna sequence. Wouldnt they just have some random bases?