How do i sketch the equipotential lines ?

the equipotential lines are perpendicular to the electric field lines.

 

Your textbook should have rules for drawing electric field lines or something like that. It says that the lines must begin on a positive charge and terminate on a negative charge. So that means that since you have one negatively charged particle, the lines will begin infinitely far away and will be directed radially inwards towards the particle. That is, the tail of the arrow is at infinity and the point of the arrow is pointing towards the particle.