what was the nature of the contest for sita`s hand?

Thee are so many different versions of this story but here is one that I hope helps,

King Janaka of a neighboring kingdom despairs that nobody can do the Engagement Challenge he put to anybody wanting to marry his beautiful daughter Sita, as many suitors have tried and failed to even lift the bow of Shiva (he had ordered it to be strung). Rama, naturally, manages to actually break the bow, and marriages are arranged left and right between the two kingdoms. Rama ends up marrying Sita, and the characters reside in peace for a while.