Complex sentence: She made her film debut in 1948 movie serial "Congo Bill", and worked for Warner Bros. in 1950 and for RKO Radio Pictures in 1950-52 before signing with Columbia Pictures in 1952.
Split into simpler sentences: She made her film debut in 1948 movie serial Congo Bill. She had stints as a starlet at Warner Bros. in 1950 and RKO Radio Pictures in 1950-52 before signing with Columbia Pictures in 1952.