You can't reach there by train.
1) Go till ambala in train and get a bus from there normal bus will cost around 600 and volvo will cost 900-1000
2) Take bus from sec 43 which will cost from 1k-1.5k depends on demand and season.
There are no trains to Manali,go to Manali either by bus from Chandigarh or hire a cab from Chandigarh if you are travelling with a group so that you can avoid high local taxi rates in manali.