Hi shalini!
Thanks for contacting us with your question!
You are looking for xAxis.ordinal property, which makes sure that points are spaced equally regardless of the time, distance and different similar factors. It is available in the Highstock package. You can check the simple demo below.
shalini,
In your case, you should use xAxis.tickPositioner function to calculate ticks along with xAxis.ordinal set to true. To rotate labels you can use xAxis.labels.rotation property and set and as you would like to or use the default setting of auto-rotation labels on xAxis based on chart width (or set it individually). You can read more about these properties in the API documentation.